Sure, I think that's totally reasonable.

I will make one last pitch though that if you don't want to spend the hour putting together a full box or researching it, the most primitive filter you can build that will (as far as I can tell, again take my opinions on VOCs with a grain of salt) be decently competitive with commercial filters and will require less time to find the parts for and put together than you'll spend researching commercial purifiers is:

- 1 20 inch box fan (any brand) from any store

- A 20x20 MERV13 filter or equivalent (FPR 10 if you're buying from Home Depot), these will all be located right next to the commercial filters/purifiers in any store that sells them.

- An activated charcoal filter (optional if you care about odor or VOCs, aprox 20x20 but it's likely okay if you go a bit smaller). Will likely also be next to the purifiers/filters in any store.

- Duck tape or string in a pinch if you don't have tape.

Tape them all together (make sure that arrows on the side of the filter point in the same direction as the fan is blowing) and run the fan at speed 2 or 3; don't worry about building a fan shroud or perfectly aligning things.

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That comes at the cost of:

- Extra noise

- General ugliness

But it will still perform pretty decently well and takes less time to set up than it will take to read the instruction manual for a commercial purifier. The noise from running the fan at full speed is a downside though, so I'm not knocking anyone who wants to go commercial for an out-of-the-box solution -- just saying that if what's putting you off is the time/building requirements, you can do a hacky version of this in 3-5 minutes that will get the job done for an average small apartment, and there's basically no way to mess it up as long as you don't tape the filter on backwards.

Again though, nothing against people who want to just order something, that's a totally reasonable ask. I just don't want people to get scared away thinking this has to be a full-fledged project, it's DIY but it doesn't have to involve any measurements or tools or any particular effort beyond slapping some duck tape around a single fan.

correct, i remember discussion a long time ago that people would buy HVAC booster fans that look like inline duct fans and then put a giant bucket of pellets on the top of it to suck through

Are commercial air purifiers using something better? Part of the reason I'm skeptical of the commercial market is that when I look at the teardowns of these products they're either doing something questionable where they're sacrificing air volume for noise, or they're basically using regular filters of the same or less quality that you can buy from a store.

I don't doubt you at all that cheap filters work less well, but at the same time, what are the consumer-grade commercial purifiers that aren't using cheap charcoal filters? I don't think I've ever noticed an in-store purifier that took pellets, but maybe I missed something.

Edit: it does make me curious if with a Corsi-Rosenthal box you could hang a non-enclosed/mesh bag/basket of charcoal pellets under the fan inside of the box and if that might produce better results than attaching charcoal filters to the sides. The obvious problem that springs to mind though is that this would make the design a lot more complicated and annoying to build. Might also result in charcoal dust spread around too, which might defeat the purpose of a purifier in the first place.