NegotiatedBubblecommentedweek 11a year ago
@Girl_Scout, it's all about the MERV rating for the filter being used. You can pay for a pre-built fan+filter, but I prefer to make a homemade one because I'm cheap like that. Taping a box fan to a square filter is the most basic, but box fans cannot not pull very much air through a high MERV filter. Grow exhaust fans are higher intensity. You can make a box out of cheap rigid foam board insulation from the local hardware store and tape the fan/filter to that box.
I found one site that says powdery mildew spores are about 1-3 microns, but I would research that more. Looking at the below chart, it looks like MERV 8+ is a starting point. In general, the higher a filterโs MERV rating, the stronger a fan must be in order to pull air through that filter.
โโโโWhat is a MERV rating?
โโโโepaโคgov/indoor-air-quality-iaq/what-merv-rating
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