What kind of exhaust fan should be used for 2x2x4 grow tent?

I would think a 4inch 240 cfm fan would be overkill in 36 square footage grow tent. Would you you suggest?

DankTankerous said:

I would think a 4inch 240 cfm fan would be overkill in 36 square footage grow tent. Would you you suggest?

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I use a 200 cfl, 4 inch on a variac on my 2x4x6.


2x2x4=16 square foot. You need to exchange the air once every three minutes.

16/3= 8cfm.

Buy a bathroom exhaust.

whitebb2727 said:

I use a 200 cfl, 4 inch on a variac on my 2x4x6.


2x2x4=16 square foot. You need to exchange the air once every three minutes.

16/3= 8cfm.

Buy a bathroom exhaust.


View attachment 3717435

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Lol yeah my math was off a bit . Thanks for the recommendation. I'll be using an LED Light as well

DankTankerous said:

Lol yeah my math was off a bit . Thanks for the recommendation. I'll be using an LED Light as well

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You may not even need a inline fan.

The hardware store here has bathroom fans that are round and hook to a 4 inch and they are $40. That would work perfect.

I use a 4" inline in my 42"x42"x6', works well . Keeps room running under 80 degrees, also run a small 4" input at ground level which brings in cool air from basement floor, 90+ outside .

Awesome thread! I am also looking for an exhaust for my 2x4. How do you run power to the bathroom exhaust fan? Does it have a plug or do you need to wire one on?

Most fart fans need wiring. A cheapy can be had for less than 20$ at most hardware stores. It'd be a pain to diy it with a carbon filter intake but a little frame, ac return filter, pushing into a larger diameter carbon filter would probably be your best bet. At least that is what I would do.

RuRu.The.Half.Elf said:

Most fart fans need wiring. A cheapy can be had for less than 20$ at most hardware stores. It'd be a pain to diy it with a carbon filter intake but a little frame, ac return filter, pushing into a larger diameter carbon filter would probably be your best bet. At least that is what I would do.

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Lol Fart Fans

I would recommend nothing smaller than a 4 inch inline. That's what I use in my 2x2x4 tent and it keeps temps right around 79-82. This is with a Mars Hydro 300watt (140-150ish true watt) and 92 watts of CFL.

I use a 240cfm 6" exhaust with speed controller and 109cfm 4" fresh air booster fan with speed controller. I slow exhaust at low and intake on medium. Works super for adjusting RH & temps. Pulling fresh carbon filtered outside cool air. 6" oscillating fan. Vivosun 20x20 heat mat with temp controls for added control of my humidity. Seems to be working great.

For a tent that size you don’t need anything crazy. A cheap duct booster fan would work fine as long as you don’t use long runs of ducting or need a carbon filter. If that is the case you need an in-line centrifugal fan.

whitebb2727 said:

I use a 200 cfl, 4 inch on a variac on my 2x4x6.


2x2x4=16 square foot. You need to exchange the air once every three minutes.

16/3= 8cfm.

Buy a bathroom exhaust.


View attachment 3717435

Click to expand...

I think you mean 16 cubic feet. 2x2 is 4 square feet.

DankTankerous said:

I would think a 4inch 240 cfm fan would be overkill in 36 square footage grow tent. Would you you suggest?

Click to expand...

You would be fine with a 4 inch on a controller.

chronnie49 said:

I think you mean 16 cubic feet. 2x2 is 4 square feet.

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Length x width x height. It's cubed not squared.

whitebb2727 said:

Length x width x height. It's cubed not squared.

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Yup I know Your first post said 2x2x4 is 16 square feet. I figured it was just a mistake but I wanted to make sure the OP knew how to calculate cubic feet.

My 4" max fan helpadrops my clone tent Temps to 65 in the night ...... on the lowest speed....thinking of swapping it out for one of my lil back up old school fans ... you don't need much at all for lil girls