Review on Powerful Germ Guardian True HEPA Air Purifier: Ultimate Protection from Germs, Allergens, and Odors by Kevin Abner

I have had this unit for almost a year now. It's still very quiet and the fans run strong. He works at least 12 hours a day. The black pre-filter only killed odors for about a week. Any replacement pre-filters also only act on odors for a week. I only vacuum and wash. Simple hepa filters are very expensive to replace if you do it every 3 months as intended. I'm currently buying the largest 3M filters (2 packs) for $18 at Lowe's. You can cut 5 perfectly matching filters from one. There is a small tab on the bottom where you place the filter which you need to stick on to make it appear as if it has a 'real' filter.