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submitted 3 weeks ago* (last edited 3 weeks ago) by ITeeTechMonkey@lemmy.world to c/mildlyinteresting@lemmy.world

I recently stayed in an apartment that didnt have central air so I created a corsi-rosenthal box since the smoke from the Canadian wildfires were so bad.

After 30 days of continuous use, with very minimal periods of it being turned off, this is what the filters look like!

It's disgusting yet also so satisfying to see the filters get darker from debris, dust, and dirt.

Edit: typos

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[-] GlassHalfHopeful@lemmy.ca 134 points 3 weeks ago* (last edited 3 weeks ago)
[-] Psythik@lemmy.world 49 points 3 weeks ago
[-] baldingpudenda@lemmy.world 15 points 3 weeks ago

I got MERV 13 filters to help with my kids allergies. Inside the house, perfectly fine, but once outside it's sneezing and runny noses. It's amazing.

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[-] Korhaka@sopuli.xyz 20 points 3 weeks ago

Been aware of the general idea for a long time, but had no idea that strapping HEPA filters to a fan has a fancy name.

[-] Diurnambule@jlai.lu 7 points 3 weeks ago* (last edited 3 weeks ago)

You have to cut some cardboard and use tape too. After when your solution beat every commercial solution you are allowed to name it, just to be able to shame corpo easily.

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[-] BedSharkPal@lemmy.ca 46 points 3 weeks ago

Now imagine that, but in your lungs. Yikes.

lungs are self cleaning, dirt just dosent stay in there it gets pushed out again by tiny moving hairs

[-] BagOfHeavyStones@piefed.social 8 points 3 weeks ago

... mostly into your stomach.

[-] Ruthalas@infosec.pub 39 points 3 weeks ago

I have great news for you about what happens to the contents of the stomach!

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dont worry they mix with the microplastics down there

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[-] billwashere@lemmy.world 36 points 3 weeks ago

I totally did not realize how much real science was behind these things. I mean this design is so simple and obvious, it seems like something I would throw together because it just looks like it “should” work. And according to the research I just read they are very efficient and effective. Super cool!!!

[-] AnarchistArtificer@slrpnk.net 8 points 3 weeks ago

I think the science comes in showing that it does actually work. Like, this is so simple of an idea that I would be skeptical of if it would work if I had had the idea by myself. I'm glad that I live in a world where, if I had thought of this and wondered "is this a good idea, or am I just being dumb for thinking something so simple could work?", I am able to go online and find information and guides on this and other diy filters

[-] xorollo@leminal.space 26 points 3 weeks ago

This is a great reminder to clean my computer fans.

[-] Grass@sh.itjust.works 17 points 3 weeks ago* (last edited 3 weeks ago)

make sure you get merv 13 or higher for smoke. the filters get gross fast even with 8 but you can tell the difference when you breathe.

I have 2 to 4 of these going at all times and the 8s are full time and 13+ are periodic unless fire season.

[-] amino 7 points 3 weeks ago* (last edited 3 weeks ago)

correct me if I'm wrong but anything higher than MERV 13 has diminishing returns because of increased resistance. instead of going for increased MERV I recommend getting thicker MERV 13 because of their bigger surface area.

CR boxes rely on raw total air volume and increased ACH vs HEPA which relies on filtering as much air as possible on the first pass.

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[-] Drekaridill@feddit.is 14 points 3 weeks ago
[-] SARGE@startrek.website 17 points 3 weeks ago

It really ties the room together

[-] fmstrat@lemmy.nowsci.com 10 points 3 weeks ago
[-] expatriado@lemmy.world 11 points 3 weeks ago
[-] ITeeTechMonkey@lemmy.world 29 points 3 weeks ago

Will all of you get out of my house?!?!

[-] Sunlightl@fedia.io 13 points 3 weeks ago

Nope, the air is good here. Have any beer?

[-] Mac@mander.xyz 8 points 3 weeks ago

I saw a couple left in the fridge. Will you grab more chips while you're up, please?

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[-] kayzeekayzee 12 points 3 weeks ago

Those start out white?? I think it's time to replace mine.

[-] ITeeTechMonkey@lemmy.world 5 points 3 weeks ago

Ya, they were brand new filters from the store. I bought them along with the box fan and duct tape.

This apartment doesnt have a HVAC system (just wall mounted AC unit) so it's doing all the air filtration.

[-] The_v@lemmy.world 5 points 3 weeks ago

This is why I buy my HVAC filters in bulk 4 or 8 at a time and replace them every 3-4 months (less if there is smoke). The difference it makes in keeping the house clean is very noticable. I get very little dust accumulation except in my teens rooms because they leave their doors closed.

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[-] Taleya@aussie.zone 12 points 3 weeks ago

Christ i wish we could get these filters in au at non-arserapey prices

[-] amino 5 points 3 weeks ago

have you heard of the Ikea Starkvind filters? they're a bit smaller but you can tape together as many as you want

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[-] jared@mander.xyz 9 points 3 weeks ago

Filtering can be a rabbit hole.

[-] ITeeTechMonkey@lemmy.world 13 points 3 weeks ago

Yes it can!

I was a little miffed when i went to buy the goods for this box because i couldn't get MERV 14 filters and had to settle for MERV 13.

I plan to make a frame so i can just slide filters in each side with the fan mounted on top. I'll have to figure out a means to create a nice seal between the frame and filters so the air passes through instead of around.

[-] Mastema@infosec.pub 11 points 3 weeks ago

Flexible weather stripping for doors is good for this.

[-] ITeeTechMonkey@lemmy.world 5 points 3 weeks ago

Ohhhhh that's a great idea! Thanks for the suggestion!

[-] billwashere@lemmy.world 6 points 3 weeks ago

I really need to make one of these.

[-] otter@lemmy.dbzer0.com 6 points 3 weeks ago

Now it matches the rug & walls, though

[-] ITeeTechMonkey@lemmy.world 6 points 3 weeks ago

Funny enough I cleaned that rug after first moving in (apartment was pre-furnished) and it looked clean for a whole day.

[-] otter@lemmy.dbzer0.com 5 points 3 weeks ago

I feel ya. My house was miles away from the evacuation zone of the PacNW fires a little ways back, and the filters didn't last the month. We wore masks with filters rated for smoke whenever we had to go outside, and sealed every external seam, hoping the firefighters could get it under control in time. Thankfully, they're the public servants that actually know what that phrase means, and to the enth degree. I trust every one of them right alongside our Nat'l Park service members (rangers, et al), sight unseen.

When this nation's collapse comes to your town, remember this simple rule, fellow US peeps:

Firefighters & National Park Service? Heroes of the people, through & through.

Cops, etc.? Shoot on sight (if that's your chosen theme for the apoc, ofc.) 😅

[-] Hello_there@fedia.io 5 points 3 weeks ago

Ok. I've been looking into this a lil and there are better options than a cr box.

Housefresh has been looking into this and they recommend the nukit tempest or luggable XL or another one - think it was a Canadian brand - as the cheapest total costs over time and lowest sound and most efficient purification. All of those use regular HVAC filters which cuts down on operating cost and are quite big which cuts down electricity and sound.

So recommend getting one of those for long term use, if you have the space for it.

[-] Hello_there@fedia.io 5 points 3 weeks ago

There's also an open source tempest that you can use a CNC for and customize to your liking with a script. https://github.com/opennukit/Nukit-Open-Air-Purifier/tree/main/Nukit%20Open%20Air%20Purifier-W(all)%20v1.0

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[-] aeronmelon@lemmy.world 5 points 3 weeks ago

Good job, Captain Lovell. That’s some Apollo 13-level engineering right there.

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[-] Toldry@lemmy.world 4 points 3 weeks ago

I'm viewing this post with the Thunder app and I only see one photo: a box with a fan on top. I see no filter. Is there supposed to be a second photo?

[-] Leavingoldhabits@lemmy.world 16 points 3 weeks ago

The box is the filter

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this post was submitted on 08 Jul 2025
532 points (100.0% liked)

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