I posted a thread last summer (2011) about setting up an aquaponics system in my backyard.  As I had other projects going on I decided to spend the fall and winter reading up on aquaponics so I'd be ready to set something up this spring.

I'm going to explain the basics so you can understand the photos but the best place to get your information is at Backyard Aquaponics.  It's a forum based out of Australia, but the concepts are the same anywhere.  Honestly, I barely posted there since searching around that site answers just about any questions you have.  

In hydroponics, plants grow in a soil-less media that is cyclically flooded and then drained with fertilizer-rich water.  The plant roots absorb the nutrients/water while flooded, and then absorb oxygen when the media is drained.  The media in which the plants grow can be anything from rockwool to pea gravel.

In aquaculture, fish are grown in ponds.  Plants and weeds absorb fish waste (mainly nitrogen waste) otherwise the ammonia levels would rise to toxic levels and kill all the fish.  Alternatively, the fish are raised in pens and the water flowing through them takes care of any waste.

In aquaponics, aquaculture and hydroponics are combined.  The fish are kept in a tank of some sort and the water from this fish tank drains or is pumped into plant growth media.  The roots absorb nitrogen waste and then the clean water flows back into the fish tank.  

In aquaponics, there is an additional step.  Fish produce a lot of ammonia as waste that is disposed of in the water that surrounds them.  Plants have a difficult time absorbing ammonia but have a much easier time with nitrate.  The additional step in aquaponics is conversion of the ammonia to nitrite by Nitrosoma species of bacteria and then conversion of the nitrite to nitrate by Nitrobacter species of bacteria.  The nitrate is then absorbed by the plant roots.  The bacteria live on the surface of the plant growth media (in my case pea gravel) so the media acts in detoxifying the water for the fish.  Not only is the nitrate better absorbed by plant roots, but nitrate is far less toxic to fish than ammonia if they are both at the same concentrations.

I built a small CHIFT-PIST system and I'm planning on building a bigger one.  In this system, the water level stays contant in the fish tank (CHIFT = Constant Height In Fish Tank) and the water pump is in a sump tank (Pump In Sump Tank).  

The concept is very simple:

1) The fish tank has a drain near the top that drains into a second container filled with plant grown media.
2) This second container floods with water.
3) There is an automatic bell siphon (this is a link on how to build an automatic bell siphon) that drains the water automatically into a third container once the water reaches a certain height.

It looks like this:



In my set-up, I have a 50 gallon drum set up on the ']Posted Via AR15.Com Mobile

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Theres literature about how to deal with nitrates in Aquaria. Specifically in aquarium use.

I use a Freshwater Deep Sand Bed, which allows you to complete the Nitrogen cycle (Fixing Nitrates to free Nitrogen gas) in system.

Its a little scary because of the anoxic zones, but a well tended sand bed is not an issue.

YOu can complete the nitrogen cycle with a sand bed of about 4 inches of fine sand. Pool Filter or Play sand will work.

You know, that's a very interesting idea.  I'm familiar with the anaerobic breakdown of nitrate from all my reading.  In fact, I thought about adding a sand-filled tube with water being slowly pumped through it to my system.  I've seen some set-ups with sand-filled tubes on Backyard Aquaponics.  As you may know from reading this thread, I'm kind of opposed to putting objects like rocks into the fish tank because I don't want anything "hiding" such as dead fish or food.  But a 4" layer of sand at the bottom of the tank is definitely an attractive idea because I could still see everywhere.  I guess my only concern is whether the sand would get sucked up by the outflow pipe and end up in the grow bed.  I think that could be mitigated by raising the outflow tube a few more inches from the bottom and by putting a solid trap like delicious_bass has for fish waste between the fish tank and the grow bed.  I'll think about this some more.

The deep sand bed has piqued my interest.  Since this was posted I have been reading up on it and have never heard of it.  I don't think I could incorporate that into my grow bed tank due to my 1/2" pvc that branches off the pump and creates a swirl to keep sediment moving and eventually pulled out.  However in our raft system that is having trouble with nitrite and nitrates I have an 8" deep bed under our foam growing board that would be perfect for this!  System chemistry is my weak area that I'm trying to learn and that is a helpful chart.

The concept is very simple:  Some bacteria that live in very oxygen-poor environments use the oxygen from nitrite (NO₂) and nitrate (NO₃) as an oxygen source, thereby leaving free nitrogen gas which dissipates out of the system.  If we could have an efficient system, you could do away with the plants entirely.  Having such a system would take the burden off us because it would mean less water changes and less stress regarding nitrate in general.  However, the nitrate is free fertilizer.

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Update:  03/23/2014  Crossing the weather rubicon, p.12

---------------------High------Low

Fri Mar 28---------48°--------42°

Sat Mar 29--------50°--------32°

Sun Mar 30-------42°---------29°

Mon Mar 31------48°----------29°

Tue Apr 1---------48°---------31°


I think that this coming Friday we will reach nighttime temperatures above 27 F.  This is a critical temperature.  What I have found in the past is the 550 gallon water container will not freeze if the nighttime temperature is above 27 F along with a pump that circulates the water.  I have Friday afternoon off so I'm going to right the 550 gallon container and fill it with water and place a pump in it.  If  it all goes well, I'll put the Brown Bullhead catfish, Yellow Perch and goldfish in it.  Why is it important to get the fish in there?  The large volume does a good job of diluting the ammonia produced by the fish because of the sheer volume.  Also, doing water changes is much easier since all I have to do is run water from the garden hose into the 550 gallon fish tank.  I would keep the volume changes to 20% so as not to affect the temperature of the water too much since my well water is at 52 F year-round.  If there is any danger of freezing, I can also add some well water to bring the temperature up.  It will be a lot less stressful keeping the fish outdoors and I can clean up the garage more.

The Channel catfish are of course going to stay indoors for a while, then moved to the garage, then moved to the aquaponics system once it's all set up and running.  That will be in 6+ weeks is my guess.

Just wanted to check in and post a few pictures of our flood and drain bio filter we got up and running.  Checked on it this morning and it was breaking the siphon once every 7 minutes which is way too fast so I slowed it down but now what I have run into is that is not enough water coming in to create the vacuum that the bell siphon needs to work.  May try reducing the exit down from 1" to 1/2" because I'd like a 30 minute retention time.   The bulbous looking plants on left are Crinum lilies and in the pot to the right is jalapeño.  We have a single zucchini growing in the pot.



As you can see we have a duckweed infestation.  It's almost impossible to get rid of so we strain this out and feed some to the tilapia and the rest go to our worms with solids we pull from our drains.



Here is this mornings batch of solids I pulled from our new swirl filter.  Very anaerobic and fowl smelling but the worms love it and this is turned into fertilizer so why waste it.



We harvested the two pots of Siberian kale you see growing here and yielded 10.4 oz of greens.  They were planted March 5th so not bad for less than 1 month old.  We do a destructive harvest so the used media is given to the worms to be recycled.





Lastly here is a picture of our garden bog pond and these were my goldfish that C4 and I talked about removing from my home system because they will eat the tilapia eggs.  They look happy to me and I still get visitation rights once a week


Will try and take some exterior pictures of the green house and rain water tanks for next time.  

Thanks for posting pictures!  Any tilapia in it right now?  If so, how big?

The "retention time" is an interesting topic.  The general recommendation from Backyard Aquaponics.com is to have the entire volume of your fish tank run through the grow bed at least once per hour.  So the "dwell time" within the grow bed of the water isn't typically used as a factor in the design of the system.  It is, however, a very interesting point:  

What is the ideal amount of time that the water should be in contact with the grow bed in a flood and drain system?  You would think that this would depend on the ammonia and nitrite concentration.  You certainly do not want the water to stay in contact for any longer than it takes to remove all the ammonia and nitrite.  Any longer than that and you are wasting time that more ammonia and nitrite containing water could be in contact with the bacteria in the grow bed/bio filter.

I personally would not do anything right now with your flood and drain grow bed/bio filter if you have it running smoothly.  What I would do is check the following:

1) Are you getting the entire volume of water from the fish tank through the grow bed/bio filter at least once per hour?  This is the minimum amount of flow you need regardless of the dwell time to.  Any less than this and you will likely have a build-up of ammonia and nitrite simply because not enough water is being exposed to treatment by bacteria.

2) Are the ammonia and nitrite levels zero?  If your levels are zero with the current flow rate, then I wouldn't mess with the dwell time.  It means that your water is in contact long enough with the grow bed/bio filter to remove all the ammonia and nitrite.  If the ammonia and nitrite levels are elevated, then it would be reasonable to increase the dwell time but not at the expense of enough water flow rate to get the entire volume of the fish tank through the grow bed/bio filter every hour.

If you look at the extreme situation of an aquarium canister like the one I have right now in my basement, the dwell time for the water is extremely short.  It's basically the time it takes for the water to travel from into the bottom of the canister from the fish tank, through the various sponges and ceramic beads within the canister, and then out the top.  My guess is that the dwell time of the water in contact with the bio filter media in the filter canister is not far from 7 minutes.  I don't know the volume of the canister filter off-hand but obviously this could be easily calculated.  So a dwell time of 7 minutes as you have now seems reasonable.

I'm not writing the above for delicious_bass specifically because I know he understands all these concepts, but rather for those trying to get into this.  It's absolutely critical to keep the ammonia and nitrite levels as close to zero as possible and to use that as a guide as to whether you are doing things right or not.  Except in the beginning stages of starting my fishless system up in the spring when I artificially put ammonia (in the form of urea) into the system, and while the system is growing enough bacteria to take care of the high ammonia and the nitrite that is also produced, I strive for zero ammonia and zero nitrite.  Probably the main reason I had to deal with the recent Columnaris infection was stressing the fish with high ammonia levels.  If your fish are having problems, it's almost always:

1) High ammonia

2) High nitrites

3) Low dissolved oxygen

4) High nitrates <---------This one is less clear.

For example, the Columnaris bacteria as well as other pathogens are often already present in your system.  Stress reduces the effectiveness of the fish's immune system and this makes them less capable of fighting off infection.  

When I had my system set up last summer, I had a 55 gallon barrel with my first batch of Channel catfish fry.  They apparently had ich parasites already because I had to bring them inside into a 5 gallon bucket and raise the temperature to 85 F to kill the ich.  The water from the 55 gallon barrel was connected to the rest of my outdoor system.  Not a single fish in the outdoor system showed signs of infection from ich parasites even though they were clearly in the water.  I think that because the water quality was so good that the fish in the system had no problem resisting infection.  In all fairness, another factor is that most wild fish have at least some degree of natural immunity to ich.
 


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Thanks for posting pictures!  Any tilapia in it right now?  If so, how big?

We are at max capacity for our 150 gallon tank with 40lbs of fish last time we weighed.  I'd say 1/4 of those are one pounders.

The "retention time" is an interesting topic.  The general recommendation from Backyard Aquaponics.com is to have the entire volume of your fish tank run through the grow bed at least once per hour.  So the "dwell time" within the grow bed of the water isn't typically used as a factor in the design of the system.  It is, however, a very interesting point:  

You are exactly correct and it is a safe rule of thumb to go by.  I don't wan't to go down a rabbit hole here to keep this simple for the DIY backyard system but the flow rates should be based on the amount of fish in the system and the amount of food they are fed.  If you only have 10 fish in a 150 gallon tank then you do not need to cycle the water through the grow bed at one full exchange an hour.  This is copied and pasted from Dr. Wilson Lennard's website.  "The turnover rate of water through the fish tank is a function of the fish stocking density; the higher the density the more turnover required. The turnover rate of water through the fish tank should be at least one half of the fish tank water volume every hour where the fish stocking density is less than 15 kg/m3. For situations higher than this fish stocking density, a water turnover rate as close to one fish tank water volume per hour should be aspired to. In commercial situations, 1 fish tank volume of turnover per hour should be the minimal design criteria".

What is the ideal amount of time that the water should be in contact with the grow bed in a flood and drain system?  You would think that this would depend on the ammonia and nitrite concentration.  You certainly do not want the water to stay in contact for any longer than it takes to remove all the ammonia and nitrite.  Any longer than that and you are wasting time that more ammonia and nitrite containing water could be in contact with the bacteria in the grow bed/bio filter.

I personally would not do anything right now with your flood and drain grow bed/bio filter if you have it running smoothly.

Agreed

1) Are you getting the entire volume of water from the fish tank through the grow bed/bio filter at least once per hour?  This is the minimum amount of flow you need regardless of the dwell time to.  Any less than this and you will likely have a build-up of ammonia and nitrite simply because not enough water is being exposed to treatment by bacteria.

Let me get back with you on this one.

2) Are the ammonia and nitrite levels zero?  If your levels are zero with the current flow rate, then I wouldn't mess with the dwell time.  It means that your water is in contact long enough with the grow bed/bio filter to remove all the ammonia and nitrite.  If the ammonia and nitrite levels are elevated, then it would be reasonable to increase the dwell time but not at the expense of enough water flow rate to get the entire volume of the fish tank through the grow bed/bio filter every hour.

Our levels are a little high but we are at maximum stocking density and its time to harvest.


I'm not writing the above for delicious_bass specifically because I know he understands all these concepts, but rather for those trying to get into this.  It's absolutely critical to keep the ammonia and nitrite levels as close to zero as possible and to use that as a guide as to whether you are doing things right or not.  

Thank you but I consider myself new to this and I honestly do not fully understand all these things.  I do my best to read published materials from Dr. Lennard, Dr. Rakocy, and other forums at backyardaquaponics.  Everyone's system will be a little different but I think you summed it up well by saying if nitrite and ammonia are non existent then you are doing it right no matter how the system is set up or in what order.

Here is an aquaponics calculator that was written into a program that I find handy and a few websites I frequent when I'm not on arfcom

Aquaponic Calculator

Dr. Lennard's Website

Aquaponic Source

I will update more thoroughly hopefully by this weekend.  My indoor Channel catfish are doing well.  I've been keeping a closer eye on them and the water conditions.  My outdoor fish are now in the 550 gallon container and they are outside.  I've had some deaths but this has been a very stressful winter for them.  I planted my horseradish indoors from root cuttings and I kid you not within about 4 days a couple have sprouted green leaves.  I planted 36 plants but will likely plant more.  My plan is to use horseradish this year exclusively since it grows well even at the temperature extremes and is a nitrogen hog.  I am going to use expanded shale as a grow media.  This is a very exciting and also difficult transition time.  More later.

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Hey good to hear its finally warming up and the fish are doing better.  Looking forward to seeing your pictures when you get her up and running.  I meant to get back with pictures of the exterior of our green house and rainwater/city back up.  Water quality has VASTLY improved in both systems.  Ammonia was just a tad high in our grow bed system but I think that is just contributed to it being at max capacity.  We were having high nitrites on the raft side but as of today Nitrites and ammonia were both at zero for the first time.  Fish were active and looked great so we will probably move over 7-8 pounds from the grow bed system to alleviate the crowding.

We did have one problem that I wanted to share with you guys and get an opinion on.  Here below was what I found last week and you can see all the solids that have accumulated in our swirl filter.  What had happened here is a big clump of fish waste/food clogged the pipe that goes out of the tank into the swirl.  I was able to unscrew the 1.5" compression coupling and snake it free very easily.  When this stopped up the water in the fish tank just kept rising and rising until it spilled over the side.  When this happened our sump emptied and our backup rain water pump kicked on and filled the sump up.  The water kept spilling and emptied the rain water tank that is also hooked up to the city water.  However the valve for the city water was turned off but what I realized is in this situation we would have filled our entire system up with city chlorinated water!  Will be installing an over flow out of fish tank now.  



Here is the front of our greenhouse.



Rainwater tank



This is our three valve irrigation controller and pump assembly.  

Thanks for the pictures, delicious_bass.

I didn't forget about this thread.  I'm getting my system set up and I will do a step by step explanation of this.  I've already started and I'm going to do a more thorough job of explaining the principles of aquaponics.  Stay tuned.

I am looking forward to seeing you get up and running as I have gone through in the last month and read up.  It's all trial and error and a great learning experience for us all!

After watching the dvd's we spoke about I was able to see a few errors in our systems.  I would really like your thoughts on those once you get a chance to watch them.

I just wanted to do a short update on my home system.  C4 you are probably familiar with my home setup which is very basic.  I have a 3x10x6" deep grow bed which is gravity fed to a 150 gal tank, to a bio filter (lava rock), then to my sump.  I have not been able to find out why my PH stays at 7.8 until this morning when I finally tested my grow bed media which is 1/2" river rock pebbles.  I took a sample from the dry 1" surface and tested it in muratic acid.  The river rock has high calcium amounts which elevates my PH!  Of all the most obvious things I missed this.  I have not noticed any plant deficiencies nor has it hurt my tilapia but I was curious why my PH never dropped like an established system should do.  



As a rule of thumb we should never lower PH drastically but a few days ago before I did this test I added two cups of muratic acid to my system.  The next morning I checked the PH and it went from 7.8 to a 6.2.  Tilapia are very hardy and I was aware of what the results may be and this was acceptable and did not endanger my fish.  However within a three day period I checked the PH again (today) and it was already back up to 7.8.  This goes to show you have to have the right quality of grow bed media or you will never balance out your PH to a level that is beneficial to your plants and fish.  I am now looking for 3/4" shale that does not have the calcium in it.


Here is the current Ammonia, Nitrite, Nitrate levels of my home system.  I only have 15 tilapia in the 150 gal tank and my grow bed of 30sq ft is barely half full.  All the perennials in my bio filter are a little slow but coming up.  It has been a long winter here in TX and everything is behind.  

The levels look great!  I think the nitrate will come down as the perennials and other plants get growing more.  I don't even have perennials, although I wouldn't be surprised at all if horseradish would survive the winter.  What test kit are you using?  I use one from the local pet store but it involves a lot of different bottles and drops.  Kind of cumbersome.  

Yeah, I should test my expanded shale for calcium carbonate.  I did test my gravel at one point and it passed the bubble test with hydrochloric/muriatic acid.  

IIRC, Tilapia can tolerate pH up to 10 as long as it goes up slowly, but you're right to keep it closer to 7.  I was surprised to read pouring muriatic acid directly into the system.  I'd never have the guts to do that!  That's certainly one way to lower the pH.  It's interesting to see it bounce back up basically because it was all neutralized by the calcium carbonate.  

I've been working a lot on my system and taking pictures.  I have also been working on a general write-up of the new changes of using the expanded shale.  I finally got my grow bed elevated on cinder blocks.  They are stacked 3 high which is about 23" high.  The dimensions of the grow bed are 48" wide X 80" long X 15" deep.  That comes to about 250 gallons of expanded shale grow bed media.  Not too shabby.  If you use the 6 pounds of fish per 25 gallons of grow bed media rule, then that comes out to 60 pounds of fish.  Using a safety factor of 50% of that, I could support a total of 30 pounds of fish.  Here is a picture with the fish tank on the left, the new grow bed set-up in the middle, and the new sump tank set-up on the right:



I basically switched the grow bed and the sump tank position from last year.  I like it better this way so far.  I decided not to rinse the expanded shale before putting it in the system and instead flood and drain the grow bed using the garden hose until the water is essentially clear.  I'm not quite there yet.  I was hoping to start cycling the grow bed but ran out of time doing other things this weekend.  I would like to start the system maybe tomorrow.  I have some expanded shale that is covered in bacteria in the basement in the Channel catfish container, and I also have a friend who gave me two of his used sponge filters from his aquarium.  I also have to clean out my canister filter and all the gunk and washings will be collected.  So I should not have any shortage of "seed" bacteria for my system.  

A more thorough write-up is forthcoming.

I am using the freshwater API kit from petsmart.  It has a few steps to the nitrite and ammonia solutions but after hundreds of times I can do it blind folded.  I have used small amounts of muratic acid in the past to lower PH and I added it in at the farthest point away from my fish so it took about an hour to go through my growbed and trickle in the tank.  I am guessing by the time it went into the tank the PH would have been around 5 but I would need another test to confirm that.

I am eager to stay updated with your progress.  Eventually I would like to convert my grow bed to at least 12" deep and bring in the bell siphon.  I am just sold on it's concept and getting oxygen down into the deeper zones.  Everything in my home system is planted in clay pots with worm castings but the roots still come out of the pots and deep into the gravel.  

Btw

Confucius say smart man touch gravel only once, let bell siphon do cleaning.........

LOL, yeah, the automatic bell siphon is, in my opinion, a good way to get water to every nook and cranny of the grow bed.  I think it also aerates it better and since the bacteria do need plenty of oxygen to convert ammonia to nitrite/nitrate, it ensures than enough oxygen gets to all the bacteria in the system.  It is a little tricky sometimes to get just enough flow so the bell siphon triggers, but not so much flow that the siphon won't break when the grow bed is nearly empty of water.  The one drawback is that you need a good amount of depth in the fish tank as you pump a lot of water into the grow bed, so the water level can drop quite a bit if it isn't deep enough.

In my picture, the sump tank will also be a fish tank since I'll likely put my Channel catfish into it.  It's deep enough fortunately that I'm not worried that the fish will have a problem with the water level dropping.  For tilapia, it shouldn't be a problem at all since tilapia don't mind crowding either when the water level is at its lowest while the grow bed is filled and the siphon is about to trigger.  

I may be adding my bacteria tomorrow.  We will see.

Update: 05/11/2014 The Cycling Begins, p.12

DAY 1

I finally got everything lined up to begin cycling.  The new grow bed uses the sump tank from last year.  I've raised it on 6 pillars made from 6 cinder block's.  The cinder blocks were arranged 2 side by side with 2 placed side by side at a 90 degree angle from the first two, then the last 2 placed side by side at a 90 degree angle from the middle two blocks.  I had help with the 3/4" treated plywood boards.  I have a guy who does other work for me bring them by and he cut off the ends so it was 80 inches long (6'8") and 4' wide.  This is the approximate dimension of the bottom of the sump tank.  I put two layers of the plywood which comes to approximately 1 1/2".  The cinder blocks 3 tall comes to 23" so the grow bed is 24 1/2" off the ground/gravel.

Empty grow bed in the middle set up on cinder blocks and pressure-treated plywood:



Other angles:








Using a hole saw, I drilled through the plastic bottom of the grow bed and through the plywood.  I then used the hole saw bit to enlarge the wood portion so I could put a Uniseal flexible tank/bulkhead adapter.  





The plywood looks like it is more than 3/4".  



Since I'm using a 2" PVC pipe for the drain, I have a 2" Uniseal adapter.  The actual hole I drilled is 3" in diameter as it needs to be a bit bigger to accommodate the Uniseal.





The 2" PVC stand pipe is then inserted into the Uniseal adapter.  Make sure you wet it first or you will have a hard time getting it into the hole.  This is another reason why the wood below has to be cut even larger so it doesn't impede the passage of the pipe.  You can use saliva to lubricate.  I wanted to avoid using dish soap but a small amount will wash away and shouldn't affect the fish at all.



The attachment is a little more complicated.  Here you see the stand pipe below the grow bed.  I didn't want to glue everything in place because you can only use a saw to take it apart, but I also recognize that over time the hand-fit pieces will work loose.  So what I did was put a few layers of teflon tape around the male end of the PVC pipe, then inserted this into the 90-degree angle PVC, then put some duct tape over that.  It's not going anywhere, but it also allows me to change things around easily instead of having to cut glued pieces off with a PVC saw.  The last two years I didn't even use teflon or duct tape but just hand-fit the PVC pieces.  I then put a wood dowel under the 90 degree angle PVC connection so it further ensures that it says in place.  









Next I added a length of PVC with teflon/tape to keep in place, and ran it through a 3" hole in the sump tank:







The set-up of the automatic bell siphon isn't complete until the gravel/expanded shale 'guard' is pot around the stand pipe.  This is to help prevent gravel, expanded shale or grow bed material from escaping out of the grow bed into the sump tank.  I re-used the same blue bucket from last year that has 3" holes drilled into it, but I changed the screen to a much finer mesh one because there is quite a bit of finer material in the expanded shale that I bought.  IIRC, it is 3/8" material but there is a lot of finer material in there.  I don't really care as the bacteria don't care.  But, I did have to put a smaller mesh around the blue bucket to prevent all that finer material from ending up in the sump tank.  


Close-up of the finer mesh used around the gravel guard which is placed around the automatic bell siphon set-up.  Here we only see the stand pipe.  The bell portion goes over this.



Finer mesh.  Last year I used 1/2" mesh:



It's important to keep as much metal out of contact with water in your system as possible.  Plastic in the form of PVC, synthetic rubber, etc is not going to be affected by the water, and it won't rust or leach metal into the water.  Some metal is unavoidable, but you can almost always find a non-metal/plastic alternative.  Plastic zip ties are used throughout.  This fine mesh screen is made, IIRC, of a PVC coated fiberglass.  Most of the materials you'll need are available locally at Lowe's, Home Depot, etc.  





This is a great picture showing the grow bed with the stand pipe, gravel guard (ETA: this is the old one with the larger mesh size) and the pipe going into the sump tank.  I like having a lot of pictures so people can see all the perspectives and hopefully understand this well.:



That covers the outflow of the system.  As far as the inflow, I wanted to put in a pipe, maybe 7 or 8" in diameter that would go straight to the bottom of the grow bed, and into which the water will flow in from the fish tank.  This is not going to happen until the system is fully cycled, but I still wanted it all in place for when I did this.  I couldn't find exactly what I wanted, and I didn't want to use another 5 gallon bucket as it does take up more space in the grow bed than I wanted it to.  So I went to the hardware store and found some plastic end connectors and put them together into what I wanted:

3" holes drilled to allow flow out of the pipe:



Connecting the pieces was easy by punching holes and connecting the 3 pieces with plastic zip ties:





Inside view before trimming the zip ties:





Zip ties trimmed:



Since I didn't want expanded shale pouring into the holes, I put 1/2" plastic screen around my pipe.  Again, zip ties were used to secure it in place:







Since I had already filled the grow bed, I had to dig out some expanded shale and put in the pipe.  This is what the water from the fish tank will flow into.  It will give a place for the water to go and avoid a lot of splashing onto the leaves which can cause fungal and other diseases to flourish.  You can see the hole where the pipe from the fish tank will come in:



As noted, I am using expanded shale for the grow bed instead of gravel.  



I put the stand pipe at 15", so the dimensions of the grow bed are 80 inches long X 48" wide X 15" deep.  This gives 57,600 cubic inches or 249.35 gallons.  I'm rounding it off to 250 gallons since the bed is slightly tapered going up, so there is likely several more gallons, maybe even up to 10 gallons or more of space in there.  I'll use 250 gallons as a nice round numbers.  This is 946 liters in case you were wondering.  The volume of grow bed material is a critical numbers since it tells us how much material there is for bacteria to grow on, and therefore how much bacteria we have available for processing ammonia and other fish waste.  The shale was just shy of the 15" needed so I did fill a 10 lb onion bag with 3/8" gravel and buried it under the shale in one corner so I could raise the expanded shale a little more.  Ideally, you want at least 1 to 2" of grow bed material above the water line ie. the top of the stand pipe so everything stays dry on the surface of the grow bed.  Why?  Because this prevents fungal and other diseases from affecting the plants and it also prevents algae from growing on the surface of the grow bed material.  I could have just lowered the stand pipe to 14", but I want to maximize the grow bed volume and get as much bacteria in it as possible.  

I chose not to rinse off the expanded shale before putting it into the system and instead flood and drain the system with water to rinse it.  It was a lot easier to do it this way, but when I put the bad of gravel in there, it did disturb the shale enough that the water is not crystal clear.  This isn't a big deal now because I have no fish in the system and I'm simply cycling it for bacterial growth.  I will do a water change again before adding fish and it will be crystal clear.  You really want to be able to see the fish well so inspect for disease, dead fish, uneaten food, etc.  The expanded shale is much less dense than gravel.  It also has more surface area so I will be interested in seeing how well bacteria grow on it.

Now for the food the bacteria are going to eat.  I've chosen to cycle the system with urea:



Many bacteria have the enzyme urease which breaks urea down into ammonia (NH₃) and carbon dioxide.  While the two that we are concerned with, Nitrosomonas and Nitrobacter, may not have strains that will all do this, the seeding bacteria I am using for my system likely contains dozens of species of bacteria so I'm not worried the urea won't be broken down into ammonia.



So any urea that goes into the system is quickly converted to ammonia which is the actual food that the bacteria will eat.  It's simply much easier to measure out urea than liquid ammonia.  Any source of ammonia is fine.  You could use ammonium sulfate, ammonium chloride or ammonium phosphate.  I happen to have ammonium sulfate (this as well as aluminum sulfate are used to acidify the soil for my blueberries).  You could even use ammonium nitrate, but I would not do this since you won't be able to see if your system is starting to produce nitrate as it will already be in your system!  Some even urinate into the system as there is 9 grams of urea per liter of urine.  While there is absolutely nothing wrong with doing this, and the system will cycle just fine with any source of ammonia, I have no desire to do this.  

Most aquarium hobbyists use between 4 and 8 ppm (parts per million) of ammonia to cycle their aquariums.  Remember, this is done without any fish in the system as ammonia is toxic and, as we'll go over later, the nitrite that is produced as an intermediate product is even more toxic to fish.  I'm going to shoot for 8ppm of ammonia and then check the level.  Some of the ammonia may bind to the expanded shale so I may have to dose the system a second time.  That's fine since the bacteria are growing on the expanded shale surface.  

I grew up in Canada so I like using the metric system for some measurements.  The sump tank (which used to be the grow bed the last two years) is 300 gallons total.  I don't have an exact measurement, but I would estimate the water level at about 225 gallons.  I think this is pretty close.  So . . .

225 gallon = 851.7 liters ~ 852 liters

1 ppm of a liter is 1mg so we need 852 liters X 1mg/liter = 852 mg for 1ppm in the 225 gallons of water.

But since we are shooting for 8 ppm, we will multiply 852 mg X 8 = 6816 mg = 6.816 grams ~ 6.8 grams.  That will give us 8 ppm of NH₃.  

However, we're not using ammonia, we're using urea.  For each molecule of urea hydrolyzed by , we produce two molecules of ammonia when it is broken down by bacteria:

CO(NH₂)₂ + H₂O -------------> 2NH₃ + CO₂

We want 6.8 grams of ammonia (NH₃).  Since the molecular weight of NH₃ is 17 grams/mole, the amount of ammonia we need is 6.8 grams/17grams/mole = 0.4 moles.

Since the molar ratio in the above formula is urea:ammonia = 1:2 we will need only half the number of moles of urea so 0.2 moles.  The molecular weight of urea is 60 grams/mole.  So we will need 0.2 moles X 60 grams/mole = 12 grams of urea dissolved in 225 gallons of water to obtain a concentration of 8 ppm (8 parts per million).

Why not more ammonia?  There is likely a concentration that is optimal for bacterial growth and it likely lies somewhere in the 4 to 8 ppm range.  This seems to be empirically derived from aquarium hobbyists and takes into account the generally warmer water used as well as pH optimized for fish-keeping.  From all the reading I've done, I think that you can use higher concentrations but you need to be careful because the nitrite that is formed when ammonia is oxidized is going to be toxic to the ammonia metabolizing bacteria (Nitrosomonas).  Though you should have Nitrobacter growing as well which will convert the toxic nitrite into the relatively harmless nitrate.  I would recommend keeping the initial ammonia concentration below 10 ppm.  However, if anyone here has evidence that higher concentrations of ammonia will cycle the system faster then I would gladly like to see it.

So I added 12 grams of urea to the system.



What next?  Well, I will measure the ammonia concentration in a few days.  I would like it above 5 ppm. If a lot of the ammonia is bound to the expanded shale and the concentration is below that, I will simply add more urea.  Then I will measure nitrite levels every few days to see if the bacteria are converting ammonia into nitrite.

The last part of this post will be the final step for the cycling to begin.  We have the substrate onto which the bacteria will grow, we have water flowing, and we have food for the bacteria.  All we need now is the bacteria!  I have 3 small bags of expanded shale in my indoor catfish system but I'm not going to use that yet.  I am also planning in the next day or two to clean out my indoor system's canister filter which contains sludge and other bacteria-filled material.  So that will all be going into my system in the next day or so.  What I put in there today is from my friend who keeps a 90 gallon aquarium.  The best source of bacteria for an aquaponics system is either another disease-free aquaponics system or from the filters of a well-established aquarium.  This is loaded with Nitrosomonas and Nitrobacter bacteria that is critical to get the system cycling.  

These are two sponges from one of his filter systems.  These will go right into the hole where the fish tank would usually empty but where now I have the pump from the sump tank flowing into the grow bed:







Before going into the in-flow pipe, I rinsed the sponges thoroughly in a 5 gallon bucket of water that also had all the rinsed material from my friend's filter.  





All of that bacteria-laden water was poured into the grow bed and will act as the 'seed' bacteria to eventually populate the entire grow bed expanded shale with nitrifying bacteria.  This should take about 2 to 3 weeks, maybe more depending on the outdoor temperature.

And now . . . we wait.

Everything looks text book from what I can tell I am going to go back and reread again for my own knowledge.  Cycling with urea is something I have not done in the systems I have built.  Your system is going to do great!  I will post a little more when I have had a chance to re read.  Our raft system is not doing good at all.  For the last 3 days I have been doing 1/3 water changes and our nitrite level is off the chart and I have been adding the recommended dose of salt.  We just don't have the biological activity in that system.  

I have been monitoring the fish very closely and the slime coat is ok, they are not lethargic nor showing any signs of stress.  Tilapia are a very resilient fish to harsh conditions but I am doing everything I can to remedy this.  

More to come in a day or so.

I think the salt has a very protective effect against nitrite poisoning, so it really depends how much salt they and the plants can tolerate.  IIRC, full-strength seawater (35 ppt salt) completely protects against nitrite poisoning (which makes cycling in a salt-water tank aquarium a little less daunting), but of course ammonia is still an issue if that is high in a salt water (seawater) system.  Tilapia and goldfish are pretty bulletproof when it comes to nitrite and ammonia compared to other fish, but even they have their limits.

Quick updates:

1) I still haven't harvested the sludge/bacteria/filter washings from the indoor system.  Hopefully tomorrow.  This is to increase the amount of bacteria.  One thing I forgot to mention was that I pumped water from the 550 gallon fish tank to use as water in the grow bed and sump tank that are cycling.  This was done because the water containing the fish has some suspended bacteria in it.  So this is the second source of bacteria for the system, the first being my friend's used sponges from his aquarium filters and washings from his filter.  The third source of bacteria will be from my indoor filter, and the fourth will be the bags of expanded shale that I have in the catfish tank.  

2) I've tentatively decided on a catfish feed for this summer.  I mentioned that I wanted to use a lower protein % as catfish are more omnivorous than carnivorous trout, and I really don't need to feed the 50% protein trout feed to them as the extra protein and subsequently amino acids are broken down to carbohydrate (burned by the fish's metabolism) and ammonia which goes right into the water.  Catfish feed should be ideally around 28 to 36% protein.  Same for Tilapia which I discussed with delicious_bass.  All that extra protein is not utilized since the catfish and tilapia have a different digestive system and metabolism than a trout.

I am NOT recommending this feed since I have not used it.  Also, do your own diligence when choosing a feed.  You may find a better choice including something that is closer and more available to you locally at the feed store.  I came to this food after a few hours of reading, including at Backyardaquaponics.com and Pondboss.com.

Here are the labels:







OK, I picked it because it has a picture of a catfish and Tilapia on the front.  Not really.  It was recommended by a lot of people and contains fish meal as the source of protein which I think will be easier to digest.  Overall, the list of ingredients seemed better than some other feeds.  It's also Made in the USA.  Now if I was raising thousands of catfish commercially, I'd maybe decide on something else as it is more expensive than other feeds.  

More hopefully in the next couple of days.

ETA:  I placed the order by phone to a place in MA.  Hopefully it all goes well.  It's a 50 pound bag so shipping costs as much as the feed but it was cheaper than anywhere else I could find.  I'll go through prices per pound and such when I'm using it to feed the catfish so I can keep track of how much it costs per pound of fish weight gained.  It will take a while to get here.  So more waiting but that's ok since the system is still cycling.  I'll measure an ammonia level tomorrow to see if I have to add more.



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We had a good turnout for our first Aquaponics class of the year put on through the Montgomery County Master Gardner's Association.  The systems we are running at the office are really complicated for the "average" homeowner or DIY'er so we wanted to step back this year to something more basic.  When we design these systems we try to keep in mind that everyone may not be able to replicate a solids settling chamber out of fiberglass compounds and the complex steps to get the proper degree and shape.  

What we did this year is a very basic system that is a 4'x8'x8" deep grow bed that is actually two beds in one.  One half of the grow bed is designed for a raft and the other is a flood and drain deep media bed.  This offers versatility because in our experience lettuce does better in our rafts while plants like tomatoes or beets love to get their roots down into media.  This year I chose to start teaching the concept of a deep grow bed with a bell siphon because I find this so crucial in pulling the oxygen into zones and feeding the bacteria.  The raft side holds about 70 gallons and maybe 30 gallons in the media side once full.  


Both sides of the grow bed drain into our two sumps and the bell siphon breaks every 15 minutes.  We attached a breather pipe on the siphon side but I don't think that made much of a difference.  From the sump the water goes two directions, one back to the beds and the other goes directly to the fish tank.


One pipe is down into the fish tank to create a swirl that helps keep solids moving and will aid in moving oxygen around for the fish.  The other pipe is splashing over lava rock that is in a clay pot to act as a small bio filter and aids in bleeding off some of the ammonia.  There is also just a "pretty" factor here and if you are creative you could turn this into a stone waterfall.  These systems look so industrial and I want to come up with ways to add to something that is more pleasing to the eye.  


Water then leaves the fish tank from the bottom of the 2" pipe and goes into our solids filter.  Murray Hallam uses a design similar to this in his commercial systems so this is what we came up with.  Here is a 20 gallon tote with a roof louver cut to fit that will allow the solids to settle in the first portion while water goes through the screen part of the louver.  Water then passes through a series of three filters and can then exit back into the sump.  Here we would place an air stone near the filters to aid the bacteria that will also live here.  We have also added a 1" drain in the bottom of this filter.  


Cost of what you see here is $575 and similar systems that are prefabricated online start at $3500.  


Not only do we do hands on in constructing the system but teach lots of history and principles of aquaponics.


Demonstrate pump head pressure loss and basics.


Tank heaters and thermostat controller.

Nice!  I actually picked up a pond liner on clearance last year since I've thought about using a liner + a wood frame.  It is far less expensive than using a plastic container, especially for the larger sizes.

Yeah, the Automatic Bell Siphon is a great concept.  No worrying about whether oxygen is getting to all of the bacteria-covered media, and they're dirt cheap to make!  

My system is still cycling.  I actually reached a peak temperature of 62F on Saturday.  I'm hoping to connect the fish tank by June 1rst.  We had a late winter so that has really set things behind.  I'm really excited about getting the fish connected.

I have slowly turned down the indoor Channel catfish tank heater so now I'm, ironically, at 64F which is very close to outdoor temperatures.  I don't think I'll need to put the Channel catfish into the garage as a stepping stone to get them into the outdoor system since the basement temperature probably won't be too much different than the outdoor tank temperature.  

delicious_bass, you're lucky not having to deal with this temperature BS.  I've had to keep Channel catfish at 86 or 87F to kill the parasite ich, and the fish loved it!  The hotter the better.  Well, not too hot.

Update: 05/22/2014 Nitrites & Nitrates are here!, p.13

Day 11

I tested the system yesterday (05/11/2014) and I found only 0.75mg/L (ppm) ammonia.  This should be around 8mg/L (ppm)!  





I did seed the grow bed heavily with Nitrosomonas and Nitrobacter, and I also put about 1/2 gallon of expanded shale from my indoor system into about 250 gallons of expanded shale in the outdoor system.  Not much as a percentage, but now (yesterday) on day 11 of cycling the system, I have both nitrite 1mg/L (ppm) and . . .





. . . also nitrate at about 37.5mg/L (ppm)





The only water source for the grow bed/sump tank has been well water which has zero ammonia/nitrite/nitrate and the outdoor fish tank which has about 0.5mg/L of ammonia but zero nitrite and nitrate.  I actually checked the outdoor fish tank to make sure I wasn't simply transferring over nitrite and nitrate thus skewing the results.  Here is the fish tank nitrite test at zero:



This is extremely exciting (for me).  

I'm going to check the ammonia, nitrite and nitrate in a couple of days.  If the ammonia and nitrite go to zero, then I will do a water change with water from the fish tank to flush out the nitrate, and then I'll replenish the fish tank with well water and connect the system.  

I'm still a little surprised that it has progressed this fast.  We have warmer weather in the low 70's coming so this should continue to progress rapidly.  This does not mean that I have all the expanded shale covered with bacteria, that would be ridiculous given the relatively low temperatures and short period of time (it can take 6+ weeks to fully cover the grow bed media).  It simply means that a population of bacteria large enough to manage the ammonia in the water is present in the grow bed.  I will have to be very careful to only very slowly increase the feedings so the fish do not produce too much ammonia to overwhelm the system.  

I also have to remember that Nitrosomonas bacteria will grow considerably faster than Nitrobacter bacteria, and that this means there is a 'bottle-neck' between the nitrite to nitrate conversion.  This is where people often kill off all their fish in the system.  They start feeding the fish like crazy which causes ammonia to rise fast.  Nitrosomonas present can handle it, but there is not enough Nitrobacter to take the nitrite and convert it to nitrate.  Nitrite concentrations spike and react with hemoglobin in the fish's blood to produce methemoglobin which doesn't carry oxygen.  The fish suffocate despite excellent oxygen levels in the water.  I killed my Rainbow trout this way IIRC.  

The best way to prevent this is to very slowly and very cautiously increase the feeding of the fish, and to also salt the water to 2 or 3 ppt.  The chloride ion in salt displaces the nitrite ion from the fish's blood, thereby preventing the formation of methemoglobin.  

Stay tuned.

Great news on having nitrites and nitrates look like that!  Honestly I am really surprised it happened that fast due to you still experiencing cooler weather.  So just to do a short recap on your fishless cycling you added Urea and parts of a friends fish filter that had colonized bacteria correct?  As soon as the ammonia is zero do you plan on adding a few fish?  

I'm a little surprised myself.  The filters contain an enormous population of bacteria, though.  He had his aquarium at around 75 to 77F and it's a fairly heavily stocked 90 gallon fish tank.  So the population of bacteria on the filters is quite large.  Also, the filters are squeezed and the bacteria-rich water (brown water in the bucket) was poured around the grow bed to try to 'seed' the bacteria into all the nooks and crannies.  The flow of the water also helps to move the bacteria around where they eventually settle on the expanded shale all around the grow bed.  I also did, as noted above, put some expanded shale from the indoor catfish tank that already had bacteria on them and buried them in the grow bed outside.  

I'm not 'adding' the fish per se, but rather connecting the fish tank to the grow bed and running the pump from the sump tank to the fish tank.  So the water will then cycle from the sump tank ----->fish tank -----> grow bed and then back to ------> sump tank where the water circulation starts all over again.  So, yes, I'll be "adding" fish, but merely by connecting the fish tank in the circuit.  I'm still not adding the indoor Channel catfish to the sump tank.  That will come later.

I'm also not going to feed the outdoor catfish a lot.  I want to very slowly increase the feeding so they don't produce a lot of ammonia.  In this way, the bacterial population in the sump tank will not be overwhelmed by ammonia.  Instead, it will cause them to replicate and as I increase the feeding (which increases ammonia produced by the fish), the bacterial population will increase as well.  

Once I feel that the bacterial population is high enough, I can start adding some Channel catfish from the house to the sump tank outdoors.  I suspect this will not be happening until mid-June, which actually isn't that far away.  Maybe sooner depending on how warm it gets.  Warm weather = warm water = faster bacterial replication and increased activity by the bacteria that are there.  By then, the basement temperature will probably be around 65+ F and the outdoor fish tank temperature may be only a few degrees lower than that so there will be no temperature shock.


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BTW, delicious_bass, I'm going to get the API testing kit like you have.  I've had two people recommend them, including a friend of mine that does a lot of aquarium stuff, and I'd like to have two testing kits so I can confirm them against each other.  The "two is one, one is none" type of rule.

It is a great test kit.  I ordered  a gazzillion pack of replacement tubes today because we are always dropping them on our concrete floor and I'm down to my last two.  The API only comes with 4 tubes and you have 5 test if you check for low and high ph.  Let me know if you need one and I will send you a spare to make testing easier.  I went ahead and pulled the trigger on the Aquamax 4000 3lb bag for $29 from amazon.  That is expensive stuff and I am going to try a 50/50 pellets to duck weed to make it go farther.  

I added 22 tilapia to my home system making my count 37 now.  I estimate I have a total body weight of 10lbs and I am going to monitor water quality closer and cut back on food until they adjust.

We are harvesting our grow bed system this week so standby for pics.  Fish tacos to come.....

Yes, please take pictures.  I'd love to see how the tilapia is doing.

The Aquamax is considerably cheaper if you buy a 50 pound bag, but buying a small amount is wise to make sure they like it.  I know tilapia like just about anything, but you don't want to be stuck with 50 pounds of food unless you have another fish that will eat it.  Fortunately my Channel catfish seem to like it.  

Quick update:  05/26/2014  Nitrites and Nitrates higher!

Day 14

I tested the ammonia, nitrites and nitrates yesterday (05/25/2014) on Day 14 and they were as follows:

The ammonia had dropped slightly from 0.75mg/L (ppm) to 0.5mg/L.  Remember, this will have to drop to zero as one criteria for the system to be considered cycled.  This is a good sign.  It means that a population of Nitrosomonas is well-established.  It does not mean that every expanded shale stone in the grow bed is covered in bacteria, far from it.  That of course is our end-goal, but it's not necessary for the purpose of connecting the fish tank to the system.





The nitrite level is off the chart which means that it is > 5mg/L (ppm).  When aquarium or aquaponics hobbyists kill off every last fish, this is often how they do it.  Some fish such as tilapia and goldfish can tolerate high ammonia levels for a period of time.  But no fish can handle high nitrite levels.  It is uniformly lethal.  The above ammonia level can easily be tolerated by fish long-term, but not this high of a nitrite level.  This is why you do not cycle the system with fish in it.  Or at least it's not recommended.  







If you do find yourself with high nitrite levels, you can do one of two things:

1) Pray to the Nitrite gods to be merciful to your fish.  <------------This will not work.

2) Add salt but do a water change first, say 50% and add back fresh water.  Sodium chloride contains the chloride ion which displaces nitrite in the fish's body.  This will prevent nitrite from oxidizing hemoglobin to methemoglobin which cannot carry oxygen and the fish suffocate.  How much?  I would start with 1 ppt (part per thousand) but do a water change first to add fresh water.  Then, if the problem doesn't resolve quickly, I would add another 1 ppt every day to 3 ppt.  I'm not going to go into more detail than that for now, but will re-visit this topic later.

Last, but not least, I checked nitrate which had risen from around 37.5mg/L to > 100mg/L.   This is a good sign.  It means that a population of Nitrobacter is well-established.  It does not mean that every expanded shale stone in the grow bed is covered in bacteria, far from it.  That of course is our end-goal, but it's not necessary for the purpose of connecting the fish tank to the system.





Is there a concentration where nitrate does become toxic?  That's an interesting topic that I'll address at a later date.  Suffice to say that I'd like to keep it < 20mg/L, but people have raised fish with levels > 100mg/L.  My goal is to try to mimic what happens in nature, and there the nitrate levels are usually well below 20mg/L, and even < 10mg/L.

The grow bed itself is almost perfect.  There are still a couple of areas where the water level is very near the surface of the rocks, but I still have some expanded shale in the basement so I will remedy that at some point.  

A very important note about the two bacterial species.  The Nitrosomonas bacteria grow and replicate faster than Nitrobacter.  This explains why there is a bottle-necking of high nitrite levels often when cycling an aquaponics system or aquarium.  So it may still take a while for the nitrite levels to drop as it is Nitrobacter that does the conversion from nitrite to nitrate.  Everything seems to be running on track, though, so I am not worried.  

Another note is that I checked the temperature yesterday in the cycling system.  It peaked yesterday at 67 F!  This probably explains why the bacterial colonization has gone so well.  







And, finally, a quick note about oxygenation.  Here is the sump tank where the Channel catfish will go.  When filled to the level of the inflow pipe, it's about 225 gallons.  This is after the siphon has broken (I still have to explain the automatic bell siphon, I'll get to that).



There is quite a bit of algae growing on the sides of the tank.  This tank will be covered by a tarp and hopefully I'll get around to it today.



Here it is with the water flowing into it.  It's easy to see that this will cause the water to circulate well and get highly oxygenated!





Remember that it is critical for the oxygen levels to be high for both the fish and the bacteria.

I will get to the automatic bell siphon.  Now, we continue to wait on the bacteria.

Ok so let me try this again.  I got everything typed up and posted from photobucket and my hand hit something and deleted the entire post before I hit submit.

Due to the rain we have been getting we are not going to be able to harvest some of the tilapia from our grow bed system at the office.  I decided to check water quaility in my home system for the first time since adding 22 tilapia to my existing 15 a few days ago.  My PH is normally 7.8 but due to the slightly acidic rainwater entering my system through my sump I am at a 7.2 on the low ph side.  The high PH will register yellow if it is below 7.4 on the high side.


Ammonia is between .15-.20 ppm and has been nearly undetectable until I put more fish in.  The fish are constantly releasing ammonia so in my opinion this much is acceptable as long as it goes no further.  Nitrites are at 0ppm and this I am very thankful for because I was a little nervous adding that many fish at once.


Nitrates are betwen 30-40 ppm.  I agree with C4 on wanting to replicate the harmonic balance found in nature and that would be a very low nitrate but this is more difficult in a closed loop system.  Hopefully I will see this number go down once the elephant ears and potato vine really start growing a long with the crop in my grow bed.  


I wanted to post a few pictures of the additions I have made to the system.  In the grow bed I have dug out three small duckweed ponds and boy do the tilapia love that.  I have been reading up on duckweed and when I first started aquaponics I looked at it is just a nuisance that clogged up our grow beds.  I had no idea it is used for recovering nutrients from waste water, human consumable in some countries, and a great source of fish and poultry feed.  I do not want to clog up the thread on duckweed info but this website tells you all about it.  DuckWeed.


I installed a raft in the tank out of 3/4" insulation board for shade to help with the summer heat that is coming and to keep the algae out.  I do not know how well the plants are going to grow in my little pots here with the fish nipping at the roots but we will see.


Lastly here is my naked bio filter.  Once it warms up more that little elephant ear will be 5 feet tall and the potato vines will be out of control.  The few little stalks of green are dwarf papyrus.  My sump has a little water lily in it that's not doing much.
Don't know why the picture is upside down, it's right in photobucket.

Awesome!  My only recommendation is to watch the nitrite level carefully.  The Nitrosomonas bacteria are usually very good at dealing with extra ammonia.  So good, in fact, that they will rapidly convert it into nitrite and you can get a 'bottle-necking' effect and cause the nitrite to spike since the Nitrobacter can be a little slower to convert to nitrate.  If you're careful about your feeding, then it should be no problem.  

Also, in terms of adding fish, and as you already know, it's the weight of the fish and not number of fish that dictates how much ammonia they will release.  The size of the fish does also factor into it because smaller fish have a higher food consumption relative to their body size.  In other words, you will have more ammonia released by 16 fish that all weigh 1 ounce each than if you put a 16 ounce fish in the tank.  How big were the added Tilapia?

I will check my ammonia and nitrite again today.  It's cooled off so I won't be surprised if the nitrite is still high.  I have been measuring my water temperature daily in the fish tank and will post those at some point.

Minor update:  05/28/2014  Ammonia now zero but Nitrite still high.



The ammonia is now zero.  This is one of the requirements to connect the fish tank.



The nitrite is still sky high.



More to come.

Your ammonia is coming down, it's looking really good!


Also, in terms of adding fish, and as you already know, it's the weight of the fish and not number of fish that dictates how much ammonia they will release. The size of the fish does also factor into it because smaller fish have a higher food consumption relative to their body size. In other words, you will have more ammonia released by 16 fish that all weigh 1 ounce each than if you put a 16 ounce fish in the tank. How big were the added Tilapia?

I have not really thought about it that way but it makes sense.  Out of the 22 fish I added ten were half pounders with 2-3 being 3/4lb and the rest were small.  I really wanted to get a weight on them but I was so worried that they were loosing oxygen from the trip I just put them in.  When our order of shale comes in I am going to move them over to a standby tank while I clean all of the crushed river rock out of the system.  I will post my total weight and get back with you on that.

I'm really pleased with the ammonia coming down.  The Nitrobacter grow more slowly than Nitrosomonas so it's completely normal to have the ammonia drop to zero while the nitrites are still high.  
I'll check them every other day to see if they are falling.

The weight I think is helpful when trying to determine how much to feed them.  You can go by feeding to satiety, but the other option is to feed by % body weight per day depending on water temperature.  I'm sure you can find the % for tilapia.  Earlier in this thread I have a link for Channel catfish.  You've got a good amount of fish going into your system.  I'd be cautious about only going slow on the feedings!  

This is what I've been using as a scale.  It gets it to the nearest 10 grams which is enough for what I'm using it for:

Update:  06/01/2014 Nitrite Zero

Day 18

Please read this carefully since it does get a little complicated.

I measured the nitrite levels yesterday.  We have had some rain over the last 3 days and my system is completely open to the air so one of my concerns is that it would cause some overflow and dilute the nitrite.  The results were a nitrite level of zero:





This is great news, sort of.  I know it didn't rain enough to do a complete change of the water, but my concern is that the nitrites were artificially lowered because of the rain.  So I did the next logical test which was to check out the nitrates.  These were and should still be off the charts since there is no way for the nitrates to get out of the system unless they too were diluted by rain and some overflow out of the sump tank.  The water can overflow from the sump tank where the 2" PVC tubing comes into the sump tank from the grow bed.  There is a 3" diameter hole but the PVC tubing is 2" and there is no seal around the PVC pipe so water can flow out at that level where it comes into the sump tank.  None of the fish, however, are small enough to go through the opening.  

So I measured the nitrate and while still present, it was not > 100mg/L.





The Sera test (first picture) shows around 37.5mg/L and the API test (it's hard to read in the picture) shows around 40mg/L.  So both tests show approximately 40mg/L.  This is good because it shows that the tests complement each other and this is very pleasing.  40mg/L is about 50% or less of what it should be since it was > 100mg/L.  

Conclusion:  If the nitrite was 5+mg/L on 05/28/14, then it should still be measurable on 05/31/2014.  The fact that it is zero means that the bacteria did break at least half of it down to nitrate.  We knew even on 05/28/2014 that we have Nitrobacter because we'd had positive nitrates.

Here is my dilemma:  I see two main ways to proceed:

1) Drain the grow bed and sump tank and refill with water, and add ammonia (urea).  Wait until this again goes through the cycle until all of it is transformed into nitrate.  This ensures that I have a very healthy population of both Nitrosomonas and Nitrobacter.  This would be the most prudent way of proceeding.  However, I would have to cover both the grow bed and sump tank to make sure none of the water is diluted by more rain which is forecast in the next 5 days.  If one of you were to ask me what to do next, this is what I would recommend.  Our biggest concern is to provide the best environment for the fish so we should do everything we can to ensure their safety.  

2) Drain the grow bed and sump tank, refill with fresh water, and connect it to the fish tank so the system starts running today.  This has the advantage that I finally start running my system 06/01/14.  I only have a limited number of months to run the system so I would like to get things started.  I know I have a population of Nitrobacter because they did get rid of about half of the nitrites that were left.  The fish burden is relatively modest.  I can control ammonia by how much I feed the fish since they produce ammonia as waste.  I can salt the system with NaCl which would protect the fish if there was a nitrite spike, of which I think there is a low risk.  

While I would recommend #1 to any of you, especially if you live in the southern half of the U.S. and have year-round aquaponics available, I've decided to go with #2.  I think that I have a deep and broad enough understanding of the principles of aquaponics that I can follow the levels of ammonia/nitrite/nitrate as I deem necessary to prevent a toxic environment from being established.  

I will get some pictures up of the connected system which I plan on doing today.  I did measure ammonia in the fish tank and it was a little higher than I'd like, around 4mg/L, but I am going to do a complete water change.  Temperature shock should not be an issue since the well water is now at 52F and the fish tank has been in the 50's F.  So I will be starting with fresh water throughout the system plus adding 1 ppt (part per thousand) of salt today and again tomorrow to get 2 ppt in the system as a prophylaxis against nitrite poisoning.

Fish tank ammonia level below.  It's kind of a moot point since I'll be changing out all the water in the fish tank and the grow bed/sump tank.



More to come.

Quick Update:  06/07/14 Many outdoor catfish infected

Everything is looking excellent in terms of water quality.  No pictures, but the ammonia level is zero, nitrite is zero and nitrate is about 10mg/L.  I haven't "planted" the horseradish yet but they will likely go in tomorrow.  I had a little problem with them in that when they were put outdoors, the leaves were burned by the sun and it had to start over again to get acclimatized to the full sun, which they are now and have a new set of leaves.  Once they go into the grow bed I think they will take off like wildfire.

The water flow is perfect.  The Automatic Bell Siphon functions perfectly.  It all looks and functions like a well-oiled machine.

Now for the fish . . .

The Brown Bullhead Catfish are not doing well.  These were the ones that I overwintered.  Many have open sores on them and I've had several deaths.  My best guess is a bacterial infection that has caused death due to sepsis.  It could be Columnaris which can cause fin and skin infections, but at least one of the dead fish had no significant external signs of disease.  Columnaris can cause internal infection though that will not appear outwardly.  There is some fin rot.  They are, as a group, a complete mess.  I can always catch more of these so that is not the issue.  I also do want to get my Channel catfish outside but that will have to wait until the sick ones die/are culled.  I simply tried to keep too many fish over a winter that turned out to be our worst in 100 years!  It was very difficult to take care of these fish under the circumstances and they should have been eaten or legally released back into the wild.  Oh well, live and learn.

In order to salvage the remaining catfish that don't appear to be infected yet, I decided to try some of the medicated oxytetracycline feed.  This does pose the risk of harming the Nitrosomonas and Nitrobacter, but it's a calculated risk I'm willing to take at this point.  I have some experience using this with the indoor fish.  I am flying kind of blind here since I'm not sure what the bacteria is so I'm trying the oxytetracycline.  It would be kind of a pain to re-populate the tank again through fishing.

Interestingly, the 3 Yellow Perch and the 2 goldfish look great.  So that's at least some consolation.  

More to come.

Quick update:

I moved the 3 sickest-looking fish to a 10 gallon container and started medicating the water itself with antibiotics.  It's a 5 day course.  I'm really bummed about these fish, but at least my indoor catfish are looking great.

I also (finally) planted the horseradish in the grow bed.

If you recall, my horseradish was started in peat pellets:





They've grown well, but the leaves were burned when I put them outside so they had to grow a second time to finally achieve this:



The plastic mesh was then removed from the individual plants:



And then finally the peat washed off the roots.  I like not having any soil on the roots at all but that is personal preference.  A little soil won't hurt.



I really like the new set-up of the water flowing into the grow bed.  As you may remember, I assembled a long tube set inside the expanded shale so the water could splash into it and oxygenate the water.  It's working out perfectly.  The water gets oxygenated but it doesn't splash around like it did last year.  I have a mesh netting set inside the tube for now.  I am not planning on leaving it in there indefinitely, but I want to catch debri and see what kind of things flow in from the fish tank.  There are a surprising number of insects that end up in it.



Here you can see the newly planted horseradish:



I used steamer clams to mark the spots I was going to plant.  So far I have 36 horseradish plants in the grow bed and I'm likely going to plant either Mesclun Mix or something else.  Maybe cucumber.  



Fully planted side view:



Fully planted long view:



Close-up of one of the biggest plants.  





So now I only have the infected outdoor catfish to worry about.  The water quality is great.  I did end up salting to 3 ppt (parts per thousand).  This is a good move at this point mainly because I do have a trace amount of antibiotics through the medicated feed and it could kill some bacteria leading to a nitrite spike.  Also, the indoor tank is also at 3ppt.  I don't plan on keeping it that way.  I will let it slowly dilute with the rain.  The plants are planted.  Hopefully they root well.  

I literally interrupted this post to feed the outdoor catfish in the main fish tank.  They were gobbling up the feed very well so I am hopeful.  Fingers crossed.

That's it for now.

You have most certainly had your fair share of trials and tribulation getting up and running.  The harsh and unnaturally long winter up there did not help things either and that must separate the men from the boys when it comes to Aquaponics.  

I see you are having trouble with your bull heads that were overwintered, I'd say that maybe if they do not improve you should cull them to get your channel cats in the system.  If they do improve will both species live in your aquaponics fish tank?

Your horseradish plants look VERY healthy and I imagine you will have a great harvest with those. Is that bohemian radish?  Do you just plan on harvesting the leaves or whole plant?  When we grow beets in our system we just harvest the leaves.  I plant lots of mescalin lettuce mix in my home system and it is one of my favorites!  

We have not tried cucumber in the system yet, you should give one of those a try.  We did do squash and last week we took the plant out of our flood and drain bio filter.  The plant grew really health with big thick stalks and lots of foliage but no vegetables.  Not sure what happened there but the base of the plant started getting really nasty and rotten.

I will post a recap on our harvest last week but I was down with a stomach bug so I was not able to capture many pictures.  Hang in there!

1) Hopefully, I will have both species.  But I will keep the Brown Bullhead in the main 550 gallon fish tank with the Yellow Perch, and the Channel catfish will reside alone in the 300 gallon sump tank.  The sump tank has an estimated 225+ gallons of water in it when full to where the inlet pipe comes in from the grow bed.  I'd like to keep the catfish separate for many reasons, including not being sure if they will fight each other.  There are two Brown Bullhead catfish with the indoor Channel catfish right now, but they literally grew up with them so they don't seem to bother them.  

2) I'm not sure exactly what variety of horseradish I have but it has white roots and the leaves you see in the picture.  So not sure if it's bohemian horseradish or not.  I plan on harvesting the roots if they don't form a large hairball.  I did not know until recently that you could eat the leaves!  I do plan on harvesting those as well.

3) Humidity/moisture can be hard on plants.  The leaves and stems of many plants simply can't tolerate it from my experience.  It is critically important for the top of the rocks to be bone dry.  Well, that's the ideal situation, anyway.  The idea is if water splashes continuously on the surface of the rocks it will get on the plant leaves and stems and lead to fungal and other infections.  It is completely fine for some plants that love water such as watercress, but not for most plants.  You should not let the water get to more than 1" of the surface of the rocks ie. you should have at least 1" of dry rocks above the highest point of water in your system.  I am shy of about 1 gallon of expanded shale to get there.  When I bring the catfish outdoors, I'll empty the expanded shale bags from inside the house directly into the few areas in the grow bed where water still reaches the surface.  Then it will be perfect.  

4) I'll try to get a cucumber plant into the grow bed.  They've done very well in the past.

Quick Update:  06/15/2014  

1) I have had a miraculous turnaround of the 3 very sick Brown Bullhead catfish in the 20 gallon "hospital tank".  Seriously, these fish were on their deathbed and somehow I've brought them back.  I've been using antibiotics in their water and I am surprised by how well they are doing.  I'm feeding these guys earthworms for now.

2) The fish in the 550 gallon tank are doing very well and eating well.

3) I've moved 4 of the Channel catfish into the 300 gallon sump tank.  It contains closer to 225 gallons of water.  I think they are appropriately shocked by the transition due to:

a) The temperature has dropped in the last few day from around 60 in the AM to 56 F.  I have them at about 64 in the house so this was a bigger drop than anticipated.  Going from 64 to 60 is one thing, but going from 64 to 56 is a bit more of a drop than I'd wanted.  They are looking a little more active today since the water temperature got up to 63 F during the day.

b) Probably the most important factor is the amount of light.  The basement had very little.  Even with a tarp over the sump tank, it's still very bright.  I think this has had a significant effect on them.  They are hunkered down completely during the day but do seem more active at night.  I think they will have to get used to more light being around than they are accustomed to.

c) The new environment with more space and likely some chemical changes in the water, including likely a modest pH change.  I think this is the least important factor but they may be more 'shy' for a few days as a result.  I put one Channel catfish in on Thursday (3 days ago) and then 3 more yesterday.

I'll update with more details and some pictures.  Here are some teasers:



The big one weighed 300 grams, big enough to eat if it were a Brown Bullhead catfish.



The characteristic spots of juvenile Channel catfish:

Those fish do not look like they have ever been sick.  Color on the top is dark and slime coat looks very good.  How is the water quality looking after the rain you had?  Hopefully it will warm up soon to help the system finish cycling.

We are about to rework our raft system at the office and make it similar to the system we built for the last class.  We may do away with the raft all together and convert it to a flood and drain.  If you go back to the pictures I posted of the raft a few pages back, the water exits the fish tank and goes into a swirl. From there into another 55 gallon drum that is our bio filter.  So in this bio filter we suspended a large bucket with lava rock on the surface but the water enters into the bottom.   Well anything that gets sucked through the swirl filter gets trapped in the bottom, like baby tilapia!  We found 10 one inch babies that have been trapped in here for awhile now.  We have to find a way to separate these little ones and get more organized on keeping certain ages together.

Sorry I haven't updated this.  I will do so soon.  

Things are going well.  There was a little more shock in the transfer of the indoor catfish to the outdoors.  I really think most of it is due to the extra light so I'm not at all worried about them.  

There has been even more rain the last few days and some additional overflow.  Not a big deal other than the salt will get diluted.  I may use the device I bought to measure the amount of salt.

I am running into a real dilemma about using the new floating feed.  There is absolutely nothing wrong with it other than it floats too well!  Normally, catfish in a pond would come to the surface to eat it but in my set-up, that's not really happening well.  I think I'll keep trying but I'm also going to break down and order some Bio-Trout slow-sinking pellets.  The reason I wanted to use the floating pellets is because it contains 32% protein which is the ideal amount for catfish and tilapia.  I reviewed the Bio-Trout feed and the 4mm diameter sinking pellet I'm looking at has 45% protein which is actually not too bad.  It's more than I want because it will put more ammonia waste in the water, but I think 250 gallons worth of expanded shale will be more than capable of taking care of the extra ammonia to nitrate conversion, and my horseradish is growing well.

I did end up putting 6 cucumber plants in there for you.  I was going to do only horseradish but you had asked that I put cucumbers in there and I've always had good success with them.  I'm still trying to figure out a netting I will put down for them to climb up on.  I did also purely for fun plant Swiss Chard between the rows of horseradish.  I just wanted to see them germinate and I'll see how it goes.  I don't want it to get too crowded in there.  The cucumbers have plenty of space at one end.

So hopefully I will get a good write-up done this weekend.  I'm pleased so far with how it is working out.

Hey thanks for the cucumbers!  Six plants are quite a few, I planted 15 in the soil garden and I have put up 40qts so far!  Do you pickle?  

I am down to the last few scoops of the Tractor Supply catfish food and looking forward to seeing how the tilapia react to the aquamax.  When I feed them they go nuts.  The short time I had the bluegill cats in my system they would slowly come up and were slow eaters.  

Here are a few pictures of our raft system we reworked to match our demo system for the classes.  We had to drop the raft down two inches to get the flow right out of the filter.  The sediment is staying in the first part of the filter but when we open the bottom drain it only sucks out what is right beside bulkhead fitting.  This just may be as good as it gets.  

I built a simple frame around the 27 gallon filter box to keep the top from bowing out under the weight of water.  This also gives me the ability to put small cedar pickets around it and dress it up.  

Cool stuff!  I'll comment tomorrow since it's gotten late.  Let me know how they do with the Aquamax.  I may not be needing all that I have if I end up getting the slow sinking feed.  More this weekend.

In July 2012, or 2 years ago, I posted the following on page 6.  It's worth a review because I started feeding my current fish based on weight 2 days ago.  The following quoted material is a copy/past and the amount of fish is not the same.  It's the calculations I want you to focus on.



I currently have two populations of fish, those in the 550 gallon fish tank and those in the 300 gallon sump tank.  The fish in the fish tank are the Brown Bullhead catfish and 3 Yellow Perch that made it through the horrific winter.  I've added more Yellow Perch and White Perch which I will update hopefully in a few days.  For now, I will concentrate on the Brown Bullhead catfish in the 550 gallon fish tank and the Channel catfish in the 300 gallon sump tank.

1) 550 Gallon Fish Tank  

I have the following starting weights for the Brown Bullhead catfish in grams:

1)   250
2)   220
3)   200
4)   130
5)   190
6)   200
7)   130
8)   140
9)   200
10) 150
11)  150
12)  140
13)  60

Total weight:  2160 grams

The current water temperature has stayed between 60 to 70F so I should be feeding 2% body weight daily.  That comes out to:

2160 X 2% = 43.2 grams per day

2) Sump tank

I have the following starting weights for the Channel catfish in grams:

1) 60
2) 80
3) 60
4) 300
5) 90
6) 100
7) 100
8) 150

Total weight:  940 grams

The current water temperature has stayed between 60 to 70F so I should be feeding 2% body weight daily.  That comes out to:

940 X 2% = 18.8 grams per day

I've tried feeding this amount but get left-overs that collect by centrifugal forge in the middle of the sump tank.  This is a good thing since it lets me know how if there is any left-over food.  What I am going to do is cut the feedings to 10 grams and if they eat everything then start increasing the amount of food up to the 2%.  Obviously, if the water temperature goes up further between 70 to 80F, then I will increase to 3% body weight.

I still have more Channel catfish to add but I already went crazy in the last few days adding White Perch and Yellow Perch so I have to wait a while to allow for the system to stabilize.  There is going to be more ammonia added by the fish and so the bacteria will have more to eat and therefore will reproduce.  I also cleaned out the filters in the indoor system last night so I took all the sponge washings and added the bacteria from them to the outdoor system.  

I will get more pictures up but I do feel good about going over the above information.  Feeding is a very important part of this.  I am going to post some updates regarding the food I am giving them.  It will depend on whether my plans for going back to slow-sinking pellets succeed.  I'm still in the process of making that happen and will update regarding that.

More to come.

ETA:  A quick note about temperature.  It's been around 58 to 60F in the AM lately and then peaking at about 66 to 68F.

Yes, I do pickle.  My wife does it, actually.  She's very good at it and copies my mother's recipe.  They're dill pickles with dill (obviously), mustard seeds, vinegar, salt, garlic cloves and cayenne red pepper.  I am growing a bunch of garlic again this year and I really like it pickled so I will have her go heavy on the garlic.  I had a terrible crop of dill last year so this year I started with plants from the garden center and I'm growing them in ~ 4 gallon pots.  They look great and are starting to flower.  I grow cayenne red peppers for the pickles as well.  The only ingredient I don't grow is the mustard seeds.

This is an awesome write up C4.  You would do very well teaching others about aquaponics in a classroom setting.  I am going to look around and see if there is a chart like that for tilapia.  I take it to stay accurate you would need to monitor the weight on a monthly basis?  

As soon as I get my expanded shale for the grow bed, and I am dragging my feet, I am going to get a total weight and get organized on my feeding such as you stated above.  I do have bull rocks in the bottom of my fish tank but I am going to remove those permanently to be able to inspect clarity and for sinkers.  I'd also like to set up a separate tank for fingerlings because I have a few pregnant females in my tank now and the survivability will not be good.  I don't have room for much else in my home system so I have to live vicariously through the extension office systems.  

Thank you.  I do like to teach.  I imagine the percentages are similar but the temperature range is bumped up by 10 degrees F given the higher temperature requirements for Tilapia.

As far as weight monitoring, that's an interesting but easily solvable problem.  This is a link that addresses that issue.

Briefly, you can:

1) Take a sampling a fish and weigh them every two weeks.  If you have 50 fish, you can sample 10 of them and then multiply by 5.  I think it would be too stressful to take them out and weigh them, especially with the spines that the catfish have.  I think it would be easier to do this with tilapia.

2) Use the Feed Conversion Ratio (FCR) to estimate their weight and adjust feedings accordingly.

Estimated weight gain = total pounds of feed fed x 0.556 (FCR = 1:1.8)  <-----This is a predictable amount of weight gained based on how much feed you give.  

New total fish weight in pond (or fish tank) = estimated weight gain + last total fish weight  <-----You obviously need to have a starting weight as you're putting your fish into the tank.  This is easy.

New daily feeding rate = new total weight of fish X percentage of body weight  <---The percentage body weight feeding is based on water temperature as noted in my other post above.

There are other methods including "timed feeding" in the link.  I am going to use method #2.  I have the luxury of being able to see to the bottom of my tanks and look for any uneaten food.  That's a big plus and something I would recommend to anyone doing this.  As I've written before, you need to see uneaten food and dead fish.  Either can be broken down by bacteria and cause a spike in ammonia from decomposition.  It always goes back to the basic principles of aquaponics.  Ammonia and nitrite kill fast, so make sure you don't do anything to cause a spike in either one.  My system has now been cycling since ? 05/11/14 and should contain a large population of bacteria.  But I still don't need to go out of my way to stress them.  

I have ordered slow-sinking pellets for my catfish from Bio-Oregon.  The feed is mainly for trout and salmon, but I ordered the 4mm size which has 45% protein.  That's definitely on the high side in terms of percentage, but the catfish seem to like it.  I'm going to experiment a little with the floating feed as well.  

I have the three-day weekend off from work so I will update more as well.

Quick update:

I added all of the 17 Channel catfish to the outdoor sump tank as of today:

I have the following starting weights for the Channel catfish in grams:

1)   60
2)   80
3)   60
4)   300
5)   90
6)   100
7)   100
8)   150----Total 940 grams
9)   140
10) 195---07/08/14
11)  80
12)  40
13)  200
14)  120----07/11/14
15)  195
16)  100
17)  120


Total weight: 2130 grams = 4.686 lbs

The current water temperature has stayed between 60 to 70F so I should be feeding 2% body weight daily. That comes out to:

2130g X 2% = 42.6 grams per day

As a quick aside:  I managed to grow almost 5 pounds of Channel catfish starting from an estimated 7.5g (I got weights of anywhere from 4.5 grams to 8 grams) X 17 = 127.5 g or 4.5 ounces of fish in about 7 months.

I'll post some pictures of the plants this weekend.