How many cfm's for fan and what filter for 62 Cubic foot grow tent?

HippySmoke

Active Member
Alright folks, haven't grown indoors in years so need some advice. I have a 38X38X78 grow tent and I need to keep the smell IN the tent period. Legal or not my roommate's hate that skunky odor... How many cfm's ya think I'll need to keep negative pressure within the tent and circulate the air properly? will 200 do? What carbon filter would you recommend for this grow? bearing in mind I am on a budget, been out of work for some time just living off a settlement for now.

P.s. running a 400w hps without a cool tube, the hood is vented on one side.
 

kinddiesel

Well-Known Member
1000 min , carbon filter , or better get a ozone generator , its about 75 bucks, and your all set no smell. prefer ozone generator over carbon filters, any day or night of the week . to keep those hot peppers from smelling up the house
 

HippySmoke

Active Member
1000CFM's minimum for a 62 cubic foot space!? reaaaaaaaaaaally?... is that really necessary? holy damn it's a small tent 3x3x6.5
 

spek9

Well-Known Member
1000 CFM for that small of a space?! I'd almost think that CFM would suck a golf ball through a garden hose :)

I've got a 440 6" in my 2x4x5' tent and the negative pressure is very intense. Your tent is a 1/3 larger, but I'd bet it would work just as well.

-spek
 

contraptionated

New Member
I'll explain how the size of a room determines cfm output needed to keep heat in check. For example: If you had 1-600w hps open reflector in a 6' high x 15' wide x 10' long room you would probably only need a 6" regular output centrifugal. Why? Because the air space within this oversize room would take quite a while to heat up and the approximate 450 cfm rating of the fan will be able to more than catch up to the rate of rise in ambient temperature due to only 1-600w fixture (even better still if the ballast is kept out of the room). Now what would happen if we only put a 400w hps in the 62 cubic foot tent in question? Could we still get away with a 6" vortex fan? Yes, but the temperature would be slightly higher in the small tent even though there is 1/3 less wattage because of the amount of cubic foot volume being only 1/15th as much as the 10'x15' room. Now I know these examples do not pertain exactly to your question but it is a good way of understanding the general idea behind sizing fans accordingly. This is a bit off topic but relevant: since your doing a closet size tent ( small 3' x 3' footprint) please consider a slightly raised perforated reflective floor with enough ventilation holes that would equal 5x the circular mil area of whatever size exhaust port you choose. Also, try to make the exhaust opening directly center of the tent ceiling so that with this raised floor intake you will achieve an airflow that is from bottom to top for maximum heat extraction and maximum air contact with the undersides (stomata specifically) of the leaves. This type of ventilation scenario also prevents eccentric downward expansion of the hot spot around the bulb, which in turn enables you to keep the light a little closer to the plants.
 
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