Question on cfm, totally confused?

Discussion in 'First Time Marijuana Growers' started by larrytom2, Mar 26, 2013.

  1. #1 larrytom2, Mar 26, 2013
    Last edited by a moderator: Mar 27, 2013
    Ok I am planning on building a grow box, and want a carbon filter to vent and cool. Box size is expectd to be 1.5'x2.5'x4'. If I have 15 cubic feet and need to change out the air 5 times per minute that is a cfm of 45. Then if I have a 250 hps light and want to keep within 5 degrees of ambient temperature, I would need 144 cfm. Adding these two together for189 cfm. Then if I add a carbon filter figuring a 25% loss of efficientce. I would take 189 cfm multiplied by 1.25 giving me a needed cfm of 236. I am planning on venting the box back to the room so there shouldn't be much ducting involved. Am i correct on my calculations and assumptions. Would I need an inline fane with a carbon filter or would something like this work

    Http://foothillfilters.ecrater.com/p/2118807/8-x-14-activated-carbon-odor-scrubber-with-240-cfm

    Looking for something that isn't super loud as this will be in a bedroom.
    Thanks
     
  2. i have a six inch inline from max fans and even on full blast its pretty quiet. aside from some noise due to vibration i barely notice it.
     
  3. I'm still wondering if I am calculatuing my cubic feet per minuter correctly. Want to make sure I get the right fan size, but not overdue it. I heard you can have to much ventilation.
     
  4. never heard of too much ventilation. as far as your math it looks good to me.
     
  5. 6" inline fans are huge! I have a 4" in a 3' by 2' by 5' and it keeps it plenty cool in my tent. They really pump out some Air. 6" seems big for such a small grow space but then again you could just by a speed controller.
     

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