I recently brewed what was going to be a 10% imperial stout. It was a disaster. New BIAB system, bad crush, didn't have proper instruments, etc. If all you ever brew is 5-6% beers, you may never encounter this level of frustration. I hope you never do. But in any case, I learned some lessons, which hopefully will make me a better brewer, in the long run.

1) You need a yeast starter. For a big beer like this, I used a 3L starter. A stir plate would have been nice too. You can also do a multi-stage starter.
2a) Add some yeast nutrient to your big beers
2b) Select a good yeast strain with medium to high attenuation
3) Oxygen is really important. Either agitate the stuffings out of your beer, or get a beer stone + oxygen tank. Your yeast needs oxygen to thrive, and poor oxygenation is a killer.
4) Watch fermentation closely. Big beers often have problems with a STALLED fermentation. You can fix these situations, but the longer you wait, the harder it becomes. Take a gravity reading as soon as your fermentation slows down considerably (after high krausen).
5) Watch that mash temp. You'll probably need to mash on the low side 152-153 degrees. You can buy Amylase enzyme to help with fermentability http://www.northernbrewer.com/amylase-enzyme-1-lb
6) Careful with that grain bill- if you are brewing big beers, it's tempting to throw everything in there. Make sure you have enough diastatic power, and don't go overboard on adjuncts. Do some research, most ingredients have a practical limit (for example, oatmeal should rarely be more than 10% of grain bill)

I am stuck with a beer that's 1.050 FG because I wasn't' able to get fermentation going again. I'll probably bottle it anyway, but it may be a dumper. That's a lot of time and money down the drain.

How to fix a stalled/stuck fermentation:
1) you can increase the fermentation temp by 2-3 degrees
2) you can pitch more yeast
3) you can pitch more attenuating yeast
4) (nuclear option) You can pitch a small yeast starter of higher attenuating yeast at high krausen along with some yeast nutrient

This thread speaks to me. I did a 1 gallon stout kit and added a small bottle of corn syrup. It pushed the SG up to 1.140. I didn't oxygenate properly, or add nutrient. I just added the S-04 from the kit. Two days later I added a pouch of S-05. After a week stuck at 1.07 I added a pouch of champagne yeast and some nutrient. Last SG I took was about 1.065. Target was 1.04. I bottled anyways and added fizz drops. We'll see if it even ferments...  I could have bottle bombs or flat beer. Lol. I tried the last 1/2 bottle cold that night, and even flat it tasted good.

I now have a bottle of nutrient and an oxygen cylinder/reg from my small torch kit. I need a hose/wand/stone. And I need to do a true starter next time I try a big beer, which BTW will be a 5 gallon keg batch so bottle carbing won't be an issue.

1) For a big beer I would either buy 2-3 packages of yeast or make a 5 gallon batch and use that yeast (takes planning but it works)
3) You will never get to the proper oxygen level by shaking, start using an oxygen stone,will improve all your ferments
4) See above
5) Your stated mash temps are towards the middle 152 -153. Lower your temp to 140-150 to get the simple sugars.

Be careful bottling at 1.050 you could get bottle bombs.


Just my thoughts.

Bottled it last night.

On the one hand, the flavors seem to be great. On the other hand, it's just way too sweet. I am pretty happy with my grain bill and hops schedule, but surely the next attempt will feature many process improvements and some recipe tweaks to optimize.

Long story short, I was using a floating free mercury thermometer to measure temps and my mash temp was too high. How high? Probably 160 degrees. I cooled it down eventually, but not fast enough.

For those interested, here's what I was working with:

55.7% pale 2-row
10.13%  Munich Malt (light 10L)
8.86% Rolled Oats
7.59% UK Pale Chocolate
5.06% Crystal 60
5.06% Roasted Barley
5.06% Flaked Barley
2.53% Carafa II

Going to increase the percentage of base malt and reduce the oats and pale chocolate malt. Also recalculate the recipe with assumed reduced efficiency.

Your DP was fine if your would have been doing a normal mash/sparge
On large scale, we often use double mashes with very little sparge to hit our gravity
Nutrient is nice but not necessary, oxygen was your real problem. And probably pitch rate.
On our RIS, we will pitch at 1.25 million cells per liter per degree Plato and oxygenate wort inline 2 out of 3 knockouts.

Mash temp is 155