Exhaust/Intake - CFM?

Discussion in 'First Time Marijuana Growers' started by rainycity, Jan 19, 2010.

  1. Hey, whats up? Planning my first grow with some guys right now. We're trying to figure out what kind of CFM we would like from our fans and if we should run an intake/exhaust or just an exhaust. Our setup will include 250w HPS/MH Light Kit from HTG and a 36" x 33" x 40" (W x D x H) grow box. We were also considering a carbon scrubber as well.

    I read you want air to circulate 5x per min, if this is the case would we want to run a fan somewhere around 137 cfm (Grow Box is 27.5 cu. ft. x 5 = 137)? And what about intake?

    We're still in the planning stages so if you want to suggest anything feel free. Thanks in advance!
     
  2. a 4" fan should be just fine for an area that small. <- one that will connect to dryer vent. i dont know the formulas. also, with a grow room that small, i would be more apt to building one of my own carbon scrubbers or using "ona". theres plenty of posts around here on these.
     
  3. A 4" inline centrifugal vortex/valuline style fan would do you well. It's powerful enough to run with a carbon filter and an air-cooled hood if you want. You don't need an intake fan. Make a lightproof passive intake in the bottom of your box. It should be double the cross-sectional area of your exhaust so a 6" hole would be good. GL!
     

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