replying to trader_4, Iggy wrote:
Yeah, I assumed a 1" filter and not a fat-boy or electrical. I'd suspect a lot
of pet hair, drywall dust or sawdust would have a big effect and likely stop
air movement even entirely. In my case it seemed to be just a collection of
regular light and loose dust and pollen that may have actually helped to
filter new particles. Though, I was surprised the MERV rating didn't show up
as an efficiency drop.

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