[Implicated]

I've been down this rabbit hole for a while now and sadly can't seem to find the article about the filtrete vs others, but there's been some people who tested the 'load' on these furnace filters and the Filtrete filters far exceeded everyone else in terms of airflow as the filters loaded up.

Re: Filter costs - stock up when costco has them on sale, which seems like every few months. They've got Filtrete 2500 (merv 14) for 3 filters for ~$35 if I remember correctly. I use them in my CR boxes and those I built for family (which I give them with a 3 pack of new filters and also instruct them to refill during costco sales)

I built one for a local stray cat rescue where it literally sits in the middle of the living space for 10+ cats, it's 4 months now since they started using it and the filters look quite dirty but the air flow is surprisingly still very good. (4x Noctua NF-F12 iPPC 3000 fans and 4x 16"x25"x1" Filtrete 2500 filters)

Here's some info re: which merv levels work best with various fan combinations (looks like if you're going to go with higher merv you'll need the static pressure to be able to continue to pull through them with any reasonable airflow once they're getting loaded up with stuff) - https://www.cleanairkits.com/blogs/news/what-happens-to-cadr...