CleanAirKits - Brisk Box Kit

You want the brisk box with pre-assembled 6 fan kit https://www.cleanairkits.com/products/brisk-box?variant=47660329173292 Most they go on discount is like 10-15% like twice a year. I have mine (3) hooked up to smart outlets so I can turn them all on or off when I open windows, but usually they are running 24/7. I get my 3M filters at costco when they are on sale. Has been like 10 months on one filter just fine.

They are super quiet. Some people can sleep with it in their bedroom (I'm not used to white noise/airflow like a fan so I couldn't get used to it). Takes like 10-15 mins to tape the filters into a box but if it's like once a year it's no biggie compared to performance (CADR) compared to the noise. Maybe have one per floor if you have someone with allergies or live with wildfires or something. I really like mine.

I have a [Brisk Box](https://www.cleanairkits.com/products/brisk-box) running 24/7. You can choose your own filters to build it. I use the recommended 3M Filtrete MERV-13 filters, which don't seem to have an off-gassing issue. It's quiet enough that I can have a conversation in normal speaking voices while standing right next to it. And the 6-fan version uses only about a kilowatt of electricity every 3 or 4 days. It's not pretty (although you can put an artsy, gauzey fabric over the filters to dress it up) but it's very effective and economical.

Seconding air cleaners that use PC fans. The [AirFanta 3Pro](https://a.co/d/8LTLqZy) is great, but I admit a bit higher than the price point you mentioned. It moves and cleans the air quite efficiently even on the quieter speeds. I'd recommend buying from AirFanta/Adam Wong and avoiding the copycats. Clean Air Kits also has a [4-fan Brisk Box](https://www.cleanairkits.com/products/brisk-box) that does its job very quietly and consistently. I overlook the fact that it's more utilitarian than elegant, but I understand why that be a "no" for others. It has a small footprint too. One downside is that it's $104 for the kit, and the filters are an additional purchase which might not work for your budget. Plus side (at least for me) is that these filters are easy to get preordered to my local home improvement store.

if you ever feel like making your own air filter, check our r/crboxes for some inspiration. I have an coway airmega, a 6 fan cr box from NorthBox, a levoit mini, and one of the tiny ikea air filters. every room gets a different size and type of air filter according to the needs of that room.

Unfortunately that website has been completely taken over by affiliate link BS. 95% of air purifiers sold online are complete garbage. Have tried many over the last 15 years due to asthma and allergies. The only cost effective solution I found that actually works (have an air things air quality monitor so I can tell by turning on and off air purifiers) is a box using home furnace fan filters. I got one from clean air kits that uses computer fans and it's super quiet so you can sleep with it on. Mine is 4x 20*25" filters. You can make your own with box fans but they will be crazy loud. The 4 fan one is good for a small room. https://www.cleanairkits.com/?ref=ANNALE&gad_source=1&gad_campaignid=22709004639&gbraid=0AAAAA_ODbriF_jyz8Gjm983QOPyONyoIt&gclid=CjwKCAjwt-_FBhBzEiwA7QEqyI5KZ5R9_7eGZZIs3i8JuZzTyN3fsBU8lDCdZe9VxwvN-gMl4hPouhoCCpMQAvD_BwE And you don't need the most expensive filters either, in fact they work better with the mid range ratings as they have way more airflow. Mine are 10s or 11s I think...

Google “Corsi-rosenthal box”. There is nothing more effective than this without spending thousands

Because of the added surface area of the 4x filters in a corsi rosenthal setup, filter changes occur much less frequently. You’re talking 5-6 months so your cost estimations are way off there.

Then let’s also factor in how they’re more effective, more repairable, less upfront cost, and will be eternally supported as you’ll always be able to buy furnace filters and a box fan. I do agree that over the long run they’re not more cost effective (assuming companies continue to make filters for their products) but they’re still the better option

Nah it’s not subjective. Tests have been performed and CR is truly the more effective option. You’re acting like applying duct tape involves an engineering degree. One of the aforementioned [tests](https://www.rtings.com/air-purifier/learn/air-purifier-performance)

Have you heard of Corsi-Rosenthal boxes? They are DIY (make it yourself) air purifiers, the basic model is a 20" box fan plus four furnace filters, with duct tape and cardboard to seal up the bottom and to cover up the corners of the fan. You can choose the level of filtration you want. Depending where you get your stuff you can maybe do it for under $100. Whichever you choose, pre-made purifier or CR box, make sure to note the cost of replacing filters and how often you will need to do so. From what I know, the 3M Filtrete furnace filters are best to use in CR boxes since they have the least airflow resistance. Whatever level of furnace filter you get, it's not going to be as good as HEPA (the top ones are close though) \*\*but\*\* CR boxes have a lot higher airflow than air purifiers, so the air can actually get more filtered since it goes through the filters more often. You can also add carbon (VOC/gases) filter layer to a CR box if you want, though they mostly are just particle filters because their popular use is to clean air of virus.

Corsi box is where it's at. Ours is with 2'x4' filters. Sits in the foyer with high 2nd story ceilings and open to formal living, dining, and kitchen (easily 2k+ sqft), been on 24-7 for 4 years.

We built a Corsi-Rosenthal box using materials from the still-open Home Depot. All you need is four 20x20x1 MER 13 filters (coincidentally 50% off when you buy four), and a 20" box fan. It's the single best air purifier you can get, and it's one of the cheapest and most accessible. Ran us about $40 at Home Depot last night, and it cleared up all the smoke in our apartment in no time. I recommend also sealing your doors and windows with duct tape, which you'll need anyways to build the filter. Instructions for assembly: https://corsirosenthalfoundation.org/instructions/