I recently stayed in an apartment that didnt have central air so I created a corsi-rosenthal box since the smoke from the Canadian wildfires were so bad.
After 30 days of continuous use, with very minimal periods of it being turned off, this is what the filters look like!
It’s disgusting yet also so satisfying to see the filters get darker from debris, dust, and dirt.
Edit: typos
make sure you get merv 13 or higher for smoke. the filters get gross fast even with 8 but you can tell the difference when you breathe.
I have 2 to 4 of these going at all times and the 8s are full time and 13+ are periodic unless fire season.