A while ago, I installed a very simple filter for the air vent in our scope room. It barely did anything, honestly. The “filter” is nothing more than a very loose mesh of fibers.
So I’ve bumped up to a 20x20x1 inch MERV13 pleated air filter with a paperboard frame. It fits perfectly between the vent and the grate. I even did some actual tape-measuring before purchasing. :) With a little duct tape, I was able to secure and seal the filter into place, then I put the grate back on. (A 16x16x1 inch filter would have fit, too, but I would have had to remove the louvers on the vent before taping on the filter.)
I didn’t notice any reduction of air flow and the room is still under positive pressure. So I’m not concerned with straining the HVAC system of the building.
I hope that it will help keep down the dust in the scope room! I’ll check it in a few months and update.
I’ve changed the filter twice since August. Here’s a side-by-side of the new filter and filter that’s been installed for a few months. I think it’s working: