Intake size depends on a lot of factors, but the minimum passive intake size should be twice the area of the active exhaust.

So.. add another intake or make the existing one larger, whichever is most convenient.
Orzy Reviewed by Orzy on . HELP!!! Temp. Control Ok so I jus changed my grow spaces. I made one of those rubbermaid boxes. Turned out real nice. But now it seems that my temp has peaked @ 96.3. With 7 CFL's. The space is 27"L x 18"D x 15"W = 7290 cubic inches and about 4.22 cu. ft. I already have a 4" inline duct fan hooked up to the top, and of course intake. No fan on the intake though. What can I do to decrease the temp at least 10 degrees? Any input is greatly apprecieated.:thumbsup: Rating: 5