Cheap diy passive exhaust for 2.5x2.5 or 3x3

I set out on this grow to see how much I could get for the least amount of money. I try and help med card holders :wink: grow and get experience for as cheap as possible so everyone has access to meds without a dispensary. I’m gonna be pushing 4oz with 90w. I decided to try and build a diy passive exhaust so I bought the $9.99 6" clip fan from Amazon
Comfort Zone CZ6C 6-inch Quiet Portable Indoor 2-Speed Desk Fan with Clip and Fully Adjustable Tilt, White
I bought an inside dryer vent kit from Lowe’s $15.00

I attached the inside part of the air box to the fan cage with zip ties.

Then I wrapped the air box with clear packing tape to bottleneck the air flow

I suspended it in the top of my tent with plant ties wire

This is a top view
I cut the expandable dryer hose in half and ran one piece out the back for passive inlet with a crown Royal bag as a filter.

Then I clamped the other piece to the exhaust with a crown Royal bag as a filter.

I put baby powder on the exhaust filter outside and it blew it into powder and filled my room lol. So I’d say it works. Now keep in mind it works for me because I’m in a 3x3 or smaller. I don’t believe if you tried a 4x4 and up you’d get sufficient cfm air displacement. Thanks guys for looking.


Heres Peter Griffin saying your name a bunch as a present lol …that exhaust looks homemade af BUT…I think it’s awesome man…and something that almost anyone could afford and put together. RANDY! LMAO

It does. Nowhere near your light build quality. My wife is rolling. He pulled his pants up at the urinal. It does look homemade af lol because it is. I was trying to be cheap. I’ve got a ton of neighbors that can’t buy nice shit so I really set out to help them


During seedling stage, I vent with just a clip fan. I use the sleeve of the tent as my piping/air gap seal. Works well when the lights aren’t cranked up.


That’s basically what I did. Used the inside sleeve. Pulled it up to the 4" end and clamped it. Pulled the outer sleeve over that and clamped it. I keep good vpd during the day but at night when you can’t leave the tent open the humidity was too high. I have 120 bucks tops in this setup. 4 of my neighbors are trying to replicate it. I think I’ve solved the problem but I’ll know in the morning.


At night, when the temps drop, the rh will naturally rise, too.

My exhaust fan and carbon filter cost about $120, with another 20 or so for tubing and clamps. The filter gets replaced about every 3 grows. I love diy stuff, but $120 is quite expensive for a rigged up exhaust system, when a bought one isn’t much more. Just a friendly heads up. :grinning:

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Being cheap is a way of life around here lol. Also its rained today and is supposed to tomorrow so let’s hope Toledo fills up a bit. Its really low I heard

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Good idea but ull get negative pressure if you exhaust is the same size as the passive intake …u want double the diameter as passive perhaps put another fan where the passive whole is facing the other way to exchange it fairly at an even rate same fans must do same production as long as there sealed the same I would tape it all the way up past the blades so it’s more like an inline fan instead of just blowing into the whole

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No I mean the exhaust was $25. My whole setup; the tent, the canopy fan, the seed, light everything $120 all in. I have the 6" affinity for my other grows with a 6" affinity intake fan. It was just to see what I could make that the avg person could throw together.
I’ve thought about neg pressure. I have a thinner filter to use on my intake to alleviate some of the pressure. I also have a fan in front of the inlet to help pull. I built sterile rooms so it was a challenge for me to not want to just say screw it affinity here’s my money, take it lol. As I said above I have another setup this was more for someone in a small space that doesn’t have much money. I did think about taping down to the midline of the cage but I was afraid it may burn the fan up.
@Gremmall waste not, want not as they say. Lol. It really started from tallying up the cost of growing commercially for us vs what dispensary charges. The mark up is wild. So then I started wondering how to get bang for my buck using the most basic supplies. That was 4/20. Four of my neighbors went and bought the same stuff and are doing well. We all had the same rh problem tho.


Ah, well then, excellent job! :grinning:

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I’ve got you on watching now. 4 zips is better than I did on my first grow so I’d say keep tinkering lol

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First grow lol. Sheriff’s got jokes lol


Lol I’m fixing to get with the program bro. Also, I knew there was a reason I was holding on to the best buds jar till last. It was so you guys could tell me how I did. No one has smoked any but me lol. Between you and your wife who is the bigger smoker random?

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We are the same. We have been smoking together for 17 years. I guess I smoke more because I’m home more than her.

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Nice, DIY FTW! :+1:

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Thanks @elheffe702 appreciate that.

What’s the lighting setup or did I miss it

It’s a 40w 3000k blurple and a 50w 7000k white at 12".

these are from 5 days ago. 25 colas all about 2gs, size of Bic lighter about two oz dry right now (guestimating from past experience) and I think she still has 4 weeks at least of flowering so she hasn’t even put on the final push yet. I LST two plants to scrog and had to remove scrog because 1 was male. This one’s canopy is about 18x18. I can take a pic at lights on at 8 am.

What does the whole plant look like. I gotta see how everything is positioned

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I can take a current one in the morning but,

This is from a few weeks ago. The screen that it’s LST to is no longer there so the plant is raised up more. Being tied to a screen made it harder to pick up for judging when to water.

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