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fan size and ventilation question?

Discussion in 'Growing Marijuana Indoors' started by Darkstar420710, Apr 24, 2010.

  1. #1 Darkstar420710, Apr 24, 2010
    Last edited by a moderator: Apr 24, 2010
    hello all,
    i have a couple of questions im hoping someone may be able to lend some advice. My setup is a 2x2x5 1/2 dr-60 grow tent. Im running a 400 watt hps for flowering with a modified sunburst hood to make it air cooled. Hers my question, on my last grow the temps got way to hot in there and really hurt my yield. I pulled 5 1/2 oz out of 2 white castles at the end but was not able to keep the temps under 87 degrees with the tent door open and two fans blowing directly on the light. When i purchased it i bought the 100 cfm cooling fan that hydrofarm recommended but it didt cool the thing at all so i modified it to hook up and inline fan. So now to the question, My light is now at the very top of the tent and i placed a flange that comes out of the top of the tent. From there i will be running from the top of the light on the outside of the tent to a carbon filter> Fan > Muffler. It will be 25ft of insulated duct by the end of the exhaust. Actually heres the question..haha, Sorry im high:smoking: Do i need a 4 in or 6 in inline fan for this application? The filters im looking at are as follows.
    Carbonaire 4 Inch Carbon Filter
    Carbonaire 6 Inch Carbon Filter
    Active Air 4" 165 CFM In line Duct Fan $69.90
    Active Air 6" 400 CFM In-line Duct Fan $79.90

    Any help on this would be really appreciated. also if i left anything out please ask. Thanks:)
  2. Personally, I run a 6" with a speed control on my 4x4x6 tent.
  3. Do fan speed controllers help with the noise of the fan? I hear that inline fans sound like a jet. Im looking to keep the noise to a minimum. Any advice? Do you know anything about hydrofarms Active Air inline fans, Are they loud etc.. ?
  4. if your trying to keep the noise down get a vortex inline fan,
  5. #5 colafarmer, Apr 24, 2010
    Last edited by a moderator: Apr 24, 2010
    A 100CFM fan will exhaust 100cf in 15 minutes. Your grow tent is 20 CF, so the fan should be ok. I would say that if the grow tent was larger might help. That's not an option of course, so you need to bring in some cooler air at floor level. Possibly you could freeze some gallon jugs and place in front of a fan. 87 degrees dosn't seem that hot, but 80 deg would be about right, or maybe the strain couldn't handle it. With a carbon filter that might reduce air flow(exhaust) and require a larger fan.

  6. CFM stands for cubic feet per minute, not 15 ;)

    Adding 25' of hosing will require you to up the CFM. You need to calculate in the sq footage of the air in the hose and the distance of the hose now. Longer the hose, weaker the suction. Wider the hose,...weaker the suction. ;)

    Good Luck :wave:
  7. What ya smokin their LBH!!!:smoking:Read that again...LOL
  8. What,...did I smoke too much again? lol

    You wrote,
    cfm stands for cubic feet per minute

    Is it me or is it you or is it the AK48? lol

  9. Sounded right to me. :wave:

    But I'm a noob. :D
  10. Thank you everyone for your input. The problem is when the tent doors are closed with the hydrofarm cooling fan (100CFM) i was sold the tent hits well over 110 degrees, So that fan just isnt an option. The 87 degrees is with the tent completely open and two fans running directly under the light, SO much for it being stealth. LOL. Im using 2 PC fans for passive intake and the air is very cool a constant 65 degrees. Now with this setup i will be running 4 in. insulated duct with a 25 foot run from light to the end of the exhaust. I'll be starting at the light going thru a carbon filter to the fan and finally exhausting. Can anyone recommend what size fan to use as i dont want over kill on it. Also what size filter should i use, I set links in my first post if anyone has a moment and can take a look and maybe help me in the right direction. Thanks all i really appreciate it.

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