Ventilation Passive Intake

Discussion in 'Growing Marijuana Indoors' started by weedian, Nov 28, 2011.

  1. Let's say you have a (stealth) grow box which is split into two chambers (veg/flower OR mother/clones OR seedlings/big). The total volume of the planned box is about 9.3 cubic feet.

    Do you think a 250 CFM inline fan, drawing air from both chambers (hose/pipe running into each) would be enough if used in conjunction with PASSIVE intake vents?

    I think it it should, after all the CFM rating is 26 times the actual volume of the box.

    Basically, I am trying to save money and streamline the design. I would prefer passive intakes since it means less noise, less money and less electrical stuff (wiring, power bill etc).

    ANyone want to chime in? Advice from growers using passive intake most welcome!
  2. As you say, its 26 times greater than the box. The recommended ratio is 5:1, so you are way ahead of that.
  3. You sure it's only 9.3 cu ft for both chambers? What are the dimensions?
  4. #4 weedian, Dec 6, 2011
    Last edited by a moderator: Dec 6, 2011

    Sorry for the late replay, been real busy!

    Dimensions? Here you go!

    31"(H) 23" (W) 23" (W)

    In feet:
    2.6 x 1.9 x 1.9 = 9.3

    This box will verge on micro and favors big containers and LST/SCROG over height.

    If the inline fan is too noisy/otherwise unsuitable, I'm thinking about going active inlet AND outlet with two PC fans rated at 37CFM. 37CFM with an active intake should be enough for a 9.3CF, CFL (Maximum 4x130W for total of 520 watts) grow, right?

    If you're wondering why I'm using CFLs it's because of a lack of space (no room for a ballast) and heat issues. Plus, I can vary the height of the CFLs to get into dark spots etc.

    Right, advice appreciated!

    I forgot to mention that I'm going to ditch the dual chamber and use the box as a single and just let the girls get pollinated every now and again. I was playing with cloning but I'm too busy to give that system the adequate care and consideration it needs.

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