Review on Veva HEPA Filter B Replacement and Carbon Pre-Filters Pack of 2 - Compatible with Germ Guardian Models AC4900CA, AC4825, AC4850PT, AC4820 - Air Purifier Enhancement by Collin Jackson

We have been using it for several decades. I use my device 24 hours a day, 7 days a week and change the filters once a year. I've found this to work great: I installed two (2) HEPA activated carbon filters instead of one (1) as per the instructions. Every two months I take out the HEPA filter and remove the two activated carbon filters. HEPA I taps on a flat surface and knocks off fine dust. I first shake out the two carbon filters outside (a lot of hair and dust comes off). Then I take the activated carbon filters to the sink and wash them thoroughly. You lose some of the fine charcoal, but a lot of dirt is washed out. Squeeze out the water and reattach to the HEPA filter, pop back into the block and you're done. This double activated carbon filter catches so much dirt at close range that it extends the life of the paper HEPA filter by 2 times. or 3x to keep the large amount of dust trapped in the activated carbon filters away from the HEPA paper filter which could clog it. Walter from Arizona