Thread in GD got me thinking about filters. I have been getting the Home Depot pleated filters because they never have my size in the spun fiberglass (16×30×1). I think these are a merv 6 or 7 which means it is somewhat restrictive on a scale of 1 to 16 correct?  I have been changing them every two months whenever I run the A/C. I rarely ever turn the heat on during the winters. I don't have any allergies and would rather use a filter to prolong the life of my system which is going on 7 years old.

HVAC gurus, what do you recommend?

I recommend at a minimum a basic pleated filter.  The poly filters are garbage and don't filter anything smaller than a kitten.

It all depends on your system design.  It is important that the filter seals around the edge so that unfiltered air does not by pass the filter as it becomes clogged.

Any easy way to seal it?  Sticky sided foam tape? The original filter I replaced was really 1" thick. The replacements claim 1" but are closer to 3/4".

System design? How do I figure out what I have? Single story home so the ducts go up into the ceiling. The air return is just behind the unit in the main entrance and the main unit is out in the garage.

As for filter, should it be changed more often? More often with pleated as opposed to fiberglass?

Any recommended replacement intervals for thepleated in the merv 5 to 7 range?

i use the lower end 3M (600??) or the lowes/HD house brand. they arent as restrictive as the microallergen filters. change them every 60-90 days and havent had a problem in 12 years or so.

This is typically what I use until we hit "high allergy" season.  At that time I go up to over 1000.  I think I'm running an 800 right now, and change it every 2-3 months.