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  1. #1

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    Default Negative or Positive

    In a grow tent is it best for negative pressure or positive? 600w hps 1.2mx1.2m×2m.

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  2. #2

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    Negative



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  4. #3

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    Should be good with a 6" blower or 8" . All depends how you set up

  5. #4

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    Moved to grow room design & setup / ventilation
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  7. #5

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    If you have a filter attached to an extractor fan and you have negative pressure, the tent walls will be sucked in - this is negative pressure and means that the air leaving the tent is being sucked through the smell-scrubbing filter.

    If you had positive pressure (I'm not sure how) your tent would be a balloon and you'll leave Earth's gravitational pull.
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  9. #6

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    Think I might need a better fan what's attatched to my filter. As i switch my inlet fan on my tent bloons up.

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  10. #7

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    Quote Originally Posted by Bewbuds View Post
    Think I might need a better fan what's attatched to my filter. As i switch my inlet fan on my tent bloons up.

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    Make sure that your fan is extracting rather than drawing in air

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  12. #8

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    Quote Originally Posted by M_C View Post
    Make sure that your fan is extracting rather than drawing in air
    Yeah it is I can feel the pressure coming out of the ducting. So might try for a 6" fan with decent cfm what rate would I need ?

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  13. #9

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    Extraction fan should always exceed the intake , if they are matching size fans or rated similar air flow the extraction fans speed , power , air flow is reduced once the filter is attached. Negative pressure is preferable as above have said to stop smells escaping, think of ya tent or like a vacuum only sucking air in , no smell can escape because it’s constantly drawing in 🇬🇧


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  15. #10

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    Bang on, always a bigger fan sucking out through a filter and a smaller fan pushing air in.

    I have a six inch fan drawing out and a 4 inch putting in, in a 1.2x1.2x 2.0 tent, and the tent is sucking in causing neg pressure.

    I have my oscillating fan facing the same way my air is coming in. Creating a nice “cycle” of air flow.

    All the best

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