Update 25 months later: I've had this unit now for just over 2 years. Did the math, and I'm replacing the filter about every 5 months. I have a loft-style condo that is very open and high ceilings, so this is why the filters (for me) are filled sooner than the 6-8 months the ad describes. If you have this in an enclosed room of square footage mentioned in the ad, I believe you can reasonably expect to get 6-8 months out of the standard filter. Also I run it on the highest fan setting and I run it all the time; another reason my filters fill up faster. My unit continues to perform great - the filter catches a whole lot of dust; there is very visible testament when I go to change the filter!!! (Both cool and gross to see!!!) How do you know when to change the filter? There is a red "PM 2.5" light on the top of the unit. When the filter needs to be replaced, it blinks until you change it. After you change it, hold down the fan button and the timer button (which may not be visible in the moment, but on my unit, is right in the middle of all the buttons) at the same time for a few seconds, and the red blinking will stop; this resets it. Some have asked if this air purifier is loud. I personally consider it "not loud" on any of the settings, however, for me I like and want a loud fan, and so I consider it not loud enough! :) (I need multiple "white noise" sources in my condo - due to lack of soundproofing in my condo building - to try to mask unwanted noise from other parts of the building.) For those looking for a quiet purifier, the lowest fan setting is fairly quiet. And on any of the settings, it is smooth fan sound. For some of us "fan"atics, smooth sound can be important. :) I have been impressed with this unit, it is still working well after 25 months, it is still being sold, replacement filters are still always available, and so this is probably still a good purchase choice today (April 2022). Prices on the unit and the replacements filters do a bit of jumping around, I have observed. I hope you, New Customer, get them for fair, reasonable prices. A note on the two types of filters that are available out there for replacement: There is a standard one, the type that comes with the unit. And then I see another called "medical grade", almost $10-15 more than the standard type. Too many of the reviews for the "medical grade" one say that the filter is slightly too small and ill-fitting. This is something you would not want; it would fully defeat the purpose of having a good air purifier, and for buying a filter that is supposed to be "better" than the standard filter, because dust would be sucked directly into the fan area anywhere the fit of the filter is not snug. My experience has been that the standard filter is very snug - the one I put in today was super snug. This is what you want! So unless we start seeing reviews for the "medical grade" filter being upgraded to a super-snug fit, I am going to suggest that you stick with the standard filter for your replacements. At this time, I see a few different sellers on Amazon who carry them. (APH260 True Hepa Replacement Filter) A note about cigarette smoke odor: A couple of months ago, cigarette smoke odor was coming up into my condo from the condo under mine; this air purifier did not help me with that. I run my unit on the highest setting, all the time, and still smelled the odor whenever the person smoked. Many other reviews about this unit mention they had success with cigarette smoke odor reduction/removal and forest fire smoke odor reduction/removal, so if you want it for that reason, I would suggest you try this unit out and return it within the return-timeframe if it doesn't clear the odor to your satisfaction. This is something that comes down to individual personal experience, and so this unit may still work for you to reduce those kinds of odors to your satisfaction. ~~~ Have had this 5 months now, and the change filter light went on this week. The old filter was not only gray with blocked particles, it had accumulated in 3d, sticking out off the filter! Gross!! All that blocked from my lungs! Thank you, air purifier and awesome filter!! Changing filter is very easy. The overall unit is very lightweight, so you can easily move it if needed. I recommend this air purifier, but I'm sorry to see the pricing of the unit change so wildly over the last few months - (I've kept an eye on the pricing because I'm thinking of getting a second unit for the opposite end of my condo). Hoping it becomes reasonably priced again, so I can get a second unit for the other side of my condo (which is about 1000 sq ft, and I have my current unit on one end - the bedroom side of the condo.)
