20'x20'x9' Grow Room Construction Exhaust question??

Hello Everyone,

Would really appreciate some advise here about the exhaust/intake for this size room. We are only running 4 1000 watt air-cooled hoods. Only starting out with 30 plants. I'm guessing the cfm's for size has to be around 2800 cfms not including carbon filter. If you have to exchange the air 3-4 times per minute, are there centrifugal fans that can pull/push that amount air from the carbon filter,lights and out or is this a blower set-up. Any threads or sites that I might be able to see a visual would be helpful .Thanks for the help..............

Well correct me if i am wrong anyone, but the way I was taught to figure out cfm is cubic feet/5. So I came up with 720 for your size room. You want a larger cfm carbonfilter, you want to underdraw into the filter otherwise you risk the air moving through so fast that it doesnt get scrubbed completly.


The way I set up my room, its not quite your size is.. filter in one corner high near the cealing> fan> through the lights> out.
Lower corner of the opposite side of the room, ir igged up my central air conditioning to pump in air, you dont need a high powered intake, you want a negative pressure situation, so the hot smelly air is sucked into the filter like a vacume, rather than pushed out the cracks of the walls because there is a positive pressure situation. For a room that size you could get a small fan, with a control even, to make sure its not too powerful.

Hey axl thanks for the advise, though i would lkie to ask a couple of more questions if you wouldn't mind taking a few minutes. Thanks

I think you should explain more. Are you venting the hoods? If you vented the hoods at least 200 cfms per light, with minimal bends in the ducting, and then a seperate fan with carbon filter in the sealed room would do it. Good luck..... I am running 3k in 8X8.....