I wouldn't say a purifier isn't doing anything if it's on low speed. I understand in most cases you are correct ..or at least for most casuals....but for my Smart air blast mini, I can run it on speed 1 24/7 in my living area since I don't need 6ACH for pollen. All I'm saying is, it depends on the use case.
Oops sorry I misread where you said budget was $250! I'll leave this here just in case it's helpful for someone else down the line.
Looked up the C545. Claims it cleans 436 ftsq every 15 minutes (4x per hour). That would be on high speed. There are a few other purifiers that have better cleaning performance and can be quiet. When considering my recent purchase, I looked at Smart Air Mini Blast which can be run on lower speeds and still has a high CADR/CFM. I didn't like the short warranty and ongoing energy and filter costs were on the high end. Same applies to Coway Air Mega Pro x, although Coway offers 3 yr warranty as opposed to Smart Air which is only 1 year. Both of those are good units that can be run quietly on lower speeds (so I"m told). I chose to get Alen 75i, as it is quiet enough to run on highest speed which Alen claims is 375 CFM. That means it can "potentially" clean 703 sqft 4 times per hour. It is recommended though to have more than one unit if you need to cover more than a 300 sqft room/area. Retail $749-799, but have seen as low as $650 on Alen website and Lowes carries the Version 1, which is missing a few of the auto/app features and slightly less coverage (1200 vs 1400 sqft every 30 min according to Alen rep) for $523 with the basic filter (no carbon). Have two and these work well for me as I like the aesthetics and the ease of controls and can run at any speed without an annoying noise level. A bit bulky, 27x11x 18, but you can place against a wall or a couch/table because it takes in air from the sides.
I have had the Smart Air Blast Mini since 2022 and it’s been excellent. Runs daily, almost around the clock. My home set up it basically it and several CR boxes. Air quality is great and we’ve had no transmissions in the home as far as I can tell.
Just got the Smart Air mini and am very happy with it https://www.smarterhepa.com/products/smart-air-blast-mini. With your budget you could even go with the Smart Air blast.
Both.
Lots of people will pitch you very expensive solutions, but generally the best option is the same: put 3M 1500 MPR or 1900 MPR in your HVAC system (no other brand or model, 1" or 4" both have lower resistance than standard filters, $10-12 if you get multi-packs online) and change it religiously every 3 months, and **also** run air purifiers 24/7 to achieve 5 air changes per hour at under 45 decibels such as Winix 5510 (200 sqft), AirFanta 3Pro (350 sqft), Levoit Vital 200S or SP (200 sqft), CleanAirKits Luggable XL (400 sqft), Levoit EverestAir (300 sqft), or Smart Air Blast Mini (400 sqft). Housefresh has data on sub-45 decibel performance.
Lots of folks will pitch very costly systems, but this is what actually works.
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EDIT: I see now that you posted the same question in /r/ZeroCovidCommunity, so if you're going for **absolute maximum COVID protection** then I would double the requirements to 10 ACH, so simply cut all the square footage numbers for the air purifiers in half. You can also go up to 3M Filtrete 2200 MPR in your HVAC system (or higher if you have a 4" filter), but most importantly **make sure the filter holder is 100% leak-tight** using foam gasket material. Such leaks around the edges are usually the weak spot when it comes to single-pass filtration.
Good luck, nice to meet a fellow zero-COVIDer "out in the wild"
Top Air Purifiers on Reddit
1
Coway
Airmega AP-1512HH Mighty
87% positive of 126 users
Durable, effective for allergens/odors, but loud on high.
Comfortable-Let-1706
