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Thread: Ventilation at night?

  1. #1
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    Ventilation at night?

    How important is ventilation during nighttime? It is getting very cold where I live, and the intake fan is making my room a bit too cold when the lights are off. Can I turn off my ventilation during the plants' 'night' period?
    Or should I set a timer to have the fans turn the room over a couple times in the night, and on full time during 'lights on'?

  2. #2
    420 Member Cherma's Avatar
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    Re: Ventilation at night?

    What size of room? How many plants? How cold is it geting in ther room? under 65 Degrees?
    My intake fan is off 1/2 hr after lights go off, 1/2 hour before lights come on again. Temp gets to 67-69 this time of year as a low.
    My fan is on 24/7 or until it gives out.

  3. #3
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    Re: Ventilation at night?

    It's 10x20, 7ft ceilings.
    There are a total of 56 plants in there.

    With the fans on, it got 54 degrees in there the other night because it was cold as hell outside.

    Can I just turn them off completely at night? The plants are just giving off C02 as waste during the night, not taking in any nutrients or fresh air, correct?

    Basically, what I'm asking is if plants need any kind of air at night other than whatever is needed to keep them from molding,etc.

  4. #4
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    Re: Ventilation at night?

    You flowering or vegging?
    I like chiller temps when I flower.

    You should be good to kill them in the dark cycle.

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    Re: Ventilation at night?

    I am flowering.

  6. #6
    420 Member McBudz's Avatar
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    Re: Ventilation at night?

    Plants consume CO2 and produce (give off) oxygen.

    I turn everything off for the 12 hours of darkness. Mainly since I don't want the hum of the fans heard by the neighbors in the silent night. I have anywhere from 3 to 8 plants in a roughly 3 x 5 grow tent. I don't notice any adverse effects of it doing this way. Although I haven't tried any other way to see if there is a difference.

    I like your idea of setting the fans on a timer at night to refresh the air periodically. That is probably your best bet.

  7. #7
    420 Member Stix's Avatar
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    Re: Ventilation at night?

    The main time your plant requires co2 is during photosynthesis. Photosynthesis uses light energy and carbon dioxide to make triose phosphates which is the first stage of photosynthesis. No, I'm not really this smart. I looked it up . During the dark cycle your plant is not making photosynthesis. Therefore you shouldn't need to have a fresh air intake during dark hours.

    I only run my intake fan during the light schedule with great results. I keep my intake fan on a timer. It comes on about 1/2 hour after my lights come on and turns off about 1/2 hour before my lights turn off.
    Last edited by Stix; 12-13-2008 at 07:37 AM.

  8. #8
    420 Member FlyBoy's Avatar
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    Re: Ventilation at night?

    i think its nothing wrong if the temp is about 15degress over the night so the fans should work 24hrs per day to air circulates.
    grow it!

  9. #9
    New Member chuckjun's Avatar
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    Re: Ventilation at night?

    i like fly boys answer. keep the plants leaves moving with fans but limit intake of cold air below 60 degrees slows/stops plant growth/processes. i live in high humid area must keep air moving over plants to keep mold at bay. cold night temps at end of flower can add good color to buds.
    old and in the way