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submitted 1 week ago* (last edited 1 week 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 63 points 1 week ago* (last edited 1 week ago)
[-] Psythik@lemmy.world 13 points 1 week ago
[-] baldingpudenda@lemmy.world 4 points 1 week 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 8 points 1 week 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.

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"Corsi-Rosenthal Box" sounds like it's some theoretical physics thought experiment, but no it's some filters and a box fan.

Be tempted to build one of those for my shop.

[-] EnsignWashout@startrek.website 6 points 1 week ago* (last edited 1 week ago)

I'm going to start talking in vague terms about my own designs for a "Corsi-Rosenthal Box" when I want to sound smart.

It'll be great if anyone bothers to look it up.

I mean, it sounds like an Einstein-Rosen bridge.

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[-] BedSharkPal@lemmy.ca 27 points 1 week 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 6 points 1 week ago

... mostly into your stomach.

[-] Ruthalas@infosec.pub 25 points 1 week ago

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

dont worry they mix with the microplastics down there

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[-] xorollo@leminal.space 19 points 1 week ago

This is a great reminder to clean my computer fans.

[-] Taleya@aussie.zone 8 points 1 week ago

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

I read that as "our-SER-uh-pee" at first. I now have a new adjective.

[-] Taleya@aussie.zone 3 points 1 week ago

Say it in a pirate accent

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[-] amino@lemmy.blahaj.zone 3 points 1 week 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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[-] kayzeekayzee@lemmy.blahaj.zone 8 points 1 week ago

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

[-] ITeeTechMonkey@lemmy.world 4 points 1 week 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 3 points 1 week 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.

[-] Tikiporch@lemmy.world 7 points 1 week ago

Post a new one for comparison.

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[-] Grass@sh.itjust.works 7 points 1 week ago* (last edited 1 week 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.

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[-] Drekaridill@feddit.is 7 points 1 week ago
[-] SARGE@startrek.website 9 points 1 week ago

It really ties the room together

[-] fmstrat@lemmy.nowsci.com 5 points 1 week ago
[-] expatriado@lemmy.world 8 points 1 week ago
[-] ITeeTechMonkey@lemmy.world 21 points 1 week ago

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

[-] Sunlightl@fedia.io 9 points 1 week ago

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

[-] Mac@mander.xyz 5 points 1 week ago

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

[-] NJSpradlin@lemmy.world 3 points 1 week ago

Do you have the link for it? So we can all have one.

[-] TachyonTele@piefed.social 4 points 1 week ago

You're not a true lemmy unless you own The Rug

[-] NJSpradlin@lemmy.world 3 points 1 week ago

Lemmy’s ‘Upvote Soup’?

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[-] otter@lemmy.dbzer0.com 4 points 1 week ago

Now it matches the rug & walls, though

[-] ITeeTechMonkey@lemmy.world 3 points 1 week 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 4 points 1 week 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 4 points 1 week 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 4 points 1 week 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

[-] Landless2029@lemmy.world 2 points 1 week ago

I have an unfinished project to make a nukit with a power knob.

I got a cardboard proof of concept working but need to make my mark 1 out of plywood or something else.

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[-] LovableSidekick@lemmy.world 3 points 1 week ago

I'm just amazed it apparently took two people to think of taping 4 air filters together with a fan on top.

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[-] jared@mander.xyz 3 points 1 week ago

Filtering can be a rabbit hole.

[-] ITeeTechMonkey@lemmy.world 5 points 1 week 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 9 points 1 week ago

Flexible weather stripping for doors is good for this.

[-] ITeeTechMonkey@lemmy.world 5 points 1 week ago

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

[-] aeronmelon@lemmy.world 2 points 1 week ago

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

[-] billwashere@lemmy.world 2 points 1 week 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!!!

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this post was submitted on 08 Jul 2025
228 points (99.6% liked)

Mildly Interesting

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