Yep. Impractical and fugly, but okay if you don't have a spouse, children, or care about aesthetics. BlueAir Classic 500/600 series-compatible models are the th

Yep. Impractical and fugly, but okay if you don't have a spouse, children, or care about aesthetics. BlueAir Classic 500/600 series-compatible models are the the way to go. (Was tested by Consumer Reports as the cleanest and quietest combination.) Most are basically just a rugged but minimal holder box for 3 identical filters on 3 sides with a much quieter and durable fan motor, and known good filters. The air a 680i/605 delivers is verifiably <0.5 ppm across PM0.1/2.5/10, eventually cleaning indoor air volume of reasonable size and minimal door opening frequency to an AQI <5. Note: the Classic Pro CP7i new costs almost twice what a Classic 680i/605 used to cost and uses different filters that aren't as good (thinner with less area), and the price is absolutely stupid. Buy a used 500/600 series on eBay for ~$200, clean the heck out of it, and source good filters.