Air circulation

Discussion in 'Indoor Growing' started by erick herrera, Feb 12, 2018.

    erick herrera

    erick herrera New Member

    I appreciate that these threads exist. The community I seem to run into here has been a phenomenal resource.

    With that said, I am having a hell of a time figuring out what I should be using (under a budget) for air circulation. The grow shop nearby seemed to be as clueless as well; not reassuring haha.

    I am using a 3x3x6 (in feet) topogrow tent with 2 300-w led lights.

    From what I gathered, it seems like I need an inline exhaust fan at the minimum. How do I go about installing? Do I just put it in the hole on the top of the tent?

    I am also confused about carbon filtration. It seems as though with an led set up, the carbon filter would be ducted to the fan, but on the outside of the tent? Intuitively, it would seem that putting the carbon filter it on a secondary fan pulling in air would make more sense .

    With that, is an intake fan ideal? Should that be another inLine fan or is a booster fan pulling in new air a more appropriate choice?

    I can probably eventually get 2 fans, ducting, and the carbon filter Within 2 pay cycles, but what is the bare minimum I can get away with?

    Thanks in advance,


    grassy007 Well-Known Member

    For exhausting, I would suggest buying a 6" inline duct fan with plastic housing (or cheap/loud aluminum inline duct fan). Vivosun has a plastic encased one for $69. Runs quiet. Buy some 6" aluminum ducting. Take one end of the ducting and fit it into the sleeve at the tent's top opening and cinch it with draw straps. Run the ducting down to one end of the exhaust fan and secure with circular duct clamps. Then take some ducting and attach it to the other side of the exhaust fan and run that a few feet and then insert the ducting into one end of an odor absorbing muffler. Attach some ducting to the other end of the muffler and run that ducting to an exhaust port such as an open window or attic, crawlspace, etc.

    The round vent sleeve at the tent bottom is for intake of fresh air. You can buy another 6" exhaust ducting fan (a cheap aluminum one) and use some ducting attached to the vent hood and connect that ducting to a duct fan running in reverse, so it's drawing air in (instead of exhausting air).

    Some Vivosun and other exhaust fans have adjustable fan speed control so you can dial it up or down to prevent a positive or negative air flow (tent sides bulging out or tent sides being sucked in). BTW too, you want no light seeping into the tent if you are growing photo period plants.

    If you're under a budget and don't mind the louder noise that $20 in-line aluminum duct fans make, go with those for your intake and exhaust.

    Edit: I had been experimenting (and still am with subsequent grows) with a super quiet one plant 2' x 2' stealth grow tent. I bought everything 4" instead of 6" (exhaust fan, ducting, etc) just in an effort to be QUIET.

    A 4" 190 cfm VivoSun exhaust fan doesn't draw out much air at all. In fact, my 120mm pc intake fan billows out my tent. Still, for a one plant grow, it's a good environment air wise . Ha! I'll need to dial down my $12 120mm case fan so that my $69 VivoSun 190 cfm exhaust fan can keep up and not cause my tent to billow out.

    Btw, besides nasty molds and bugs, how much extra weirdness does a positive or negative air pressure in a tent impact a pot plants growth?
    Last edited: Feb 13, 2018

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