So I started growing indoors again and its been a while. I've been doing outdoors for the last 7 years. So i made my room, set up a oscillating fan with a carbon filter with a 4" exhaust fan running the filter. Now my room is 36"x36"x76". What should my cfm be? Im running at a 100 cfm with a 4" fan. Thinking of getting a bigger one to bump it up to about 200 to 300 cfm? Should the 100 be ok?
1 to 3 times cubic feet per minute. so 400 cubic ft would require a 400 cfm fan minimum. Height x width x length = cubic feet. 3 times 3 =9 times how many feet hight, say 8 or so would = about 72 cubic feet, and 5 times that is absolute max so a 350cfm fan would be overkill but max. For a quality fan check out the a/c infinity s4. The t4 has the much complained about computer brains and costs more. The a/c can be run just enough to clear cigarette smoke on low and is completly inaudible, or on high you can hear it fumigate a whole grow room in full flower. The thing is, smell varies greatly from week to week based on plant stage, so the ability to custom tailor odor to sound is a nice touch.
Most of the time, I run mine below 1 times cubic feet per minute. I am amazed what a difference strain selection makes. Just like flowers, some are more fragrant than others. The peak for me is fresh cut harvest. Then the more cfm the better. Only lasts a few days.