HVAC filters

Because of allergies, I want an excellant filter and have been using the 3M Filtrete 1250 filter. 3M rates their filters with Micoparticle Performance Rating (MPR); hence the 1250 that they say is 90% efficient. I want the usual filtering of particles, dander, etc, to include mold spores. I think spores are larger than 10 microns.
There are other filters on the market with a MERV rating. So how do I decide which is better according to ratings, and are there better filters than the Filtrete 1250 at $16 each? Oh they also have a 1750 model (93% efficiency) for $19 but I'm not sure 3% is woth $3. I have two filters and try to replace @ 60 to 90 days. Ouch!

Good questions - I'd like to know, too!

I put in the $20 one a couple weeks ago and got to thinking that over the long haul it might be worth getting an electronic filter put in - but then you have the hassle of cleaning it every month, I assume.

If found on the 3M site that the filtrete 1250 is rated at MERV 11.

You might want to consider a washable filter. Some of those are available with high Merv numbers.

You might also consider a foam prefilter to catch the big dust bunnies , which clog the filter long before it's effectiveness on the low-micron stuff dimishes. You should have an A/C guty design this, because you might need to make the return air larger, in order to have adequate CFM for the heat/cool system.