Too much fan

Discussion in 'Grow Room Design & Setup' started by friedguy, Jan 11, 2017.


    friedguy Well-Known Member

    So it's been a while since I've done a grow... years now... and I'm starting another. :bigjoint:

    Just a couple questions.

    1st question. I know the current setup I have will work just fine, but is there anything very wrong that I should be correcting?

    Panda film & PVC frame
    Each tent has a stick on zipper on each side and is velcrod at the bottoms.
    Completely light proof.
    1x 5'x2'x7' veg/flower tent (10 square feet, 70 cubic feet)
    1x 2'x2'x7' mother/clone tent (4 square feet, 28 cubic feet)

    For clones I have 1x 23W 5000K CFL on top half of mother/clone tent (above exhaust and mother to retain some heat); 18/6 Lighting
    For mothers (will be 2 bonsai) I currently have 2x23W 6500K and 2x23W 5000K CFLS (will be switching to 45W blue/white LED panel); 18/6 Lighting
    For grow tent (for 4 plants) I have a custom made panel w/ 4x 100W 660nm LED, 4x 100W 630nm LED, 4x 100W Warm White LED, 4x 100W Cool White LED (all will run at about 60% for a total of 1000W actual watts), 1x 40W 4ft UVB fluorescent for end of flowering, and 4x 10W 730nm LED for "bloom booster"
    Flowering will be using 13/11 lighting with 20 minutes of IR (5 before lights out, 15 after) for phytochrome manipulation
    In veg I will just use the cool and warm white lights at 18/6
    All lights will be off during the hottest part of the day (around 3PM)

    8" can fan max
    Exhaust fan connected with 8" R8 insulated ducting to top of grow tent
    Bottom of grow tent connected to middle of mother tent w/ 6" ducting
    Bottom of mother tent using passive 6" ducting as intake

    Medium & Grow Method:
    Clones will be in a DIY 8 station bubble cloner w/ a 70*F aquarium heater
    Mother will be a soil mix w/ potting soil and perlite and some castings.
    Grow will be a RDWC/E&F hybrid system (controlled with multiple arduinos, a raspberry pi for a database/web server and multiple sensors). I plan on using 2" net pots with no medium other than water in 5 gallon buckets.
    Scrog with screen 1' above tops of buckets

    RO Water
    GH micro and bloom
    Rhino skin
    Trying to stick to 1-1-1 for veg and 1-2-2 for flower at around 2 EC max

    Temps are under 80* F
    Humidity is under 60%
    Will be using A/C as necessary

    White Rhino

    Additional questions: So this Is my first time using a can fan. I didn't realize just HOW STRONG they are. It's separating the sticky part of the Velcro and zippers from the tents and they are losing their seal- ON LOW :shock:. How can I get the Velcro and zippers to hold up to the exhaust fan? If the Velcro and zippers won't work, what else can I use?


    dirtWeevil Well-Known Member

    you need a speed adjustment for your fan, I forget what they are called, the fan plugs into it and you adjust the fans speed with a knob, short of that you can also open up some air holes in the tent, the shaded ones at the bottom of most tents, and or the round ventilation holes

    friedguy Well-Known Member

    The fan already has a built-in speed control and it's on low. Can I add another in-line?

    Wilderb Well-Known Member

    Do you have any passive air holes?

    friedguy Well-Known Member

    Thanks dW and wilderb!

    One 6" passive intake on the clone/mother tent. The grow tent pulls from the clone tent.

    It sounds like I should add some more.
    I'll add 2 more to the grow tent since that's the one really with the problem. The mother/clone tent has negative pressure but isn't sucking itself into a black hole.

    Should I try anything else?

    Wilderb Well-Known Member

    So it sucks air from you clone room into your grow then out?
    What is your plan for odor?
    Just trying to understand your set up.

    friedguy Well-Known Member

    I'm not concerned about odor. If it becomes a problem I'll hook up a carbon filter to the exhaust fan (inside the grow tent).
    Attached is a drawing of the setup.

    Attached Files:


    meangreengrowinmachine Well-Known Member

    It WILL become a problem once you get into flower... plus a carbon filter should reduce some of your back pressure... back pressure is also great for keeping smell leaks from escaping and keeping everything going through your carbon filter...

    Wilderb Well-Known Member

    Do you get much suction in your clone room? If you have passive air intakes in your grow room that leads me to believe there isn't much air being pulled from your clone room.

    friedguy Well-Known Member

    I didn't think of the carbon filter reducing some back pressure, good point.

    I added some vents last night. The grow room now has 3x 6" passive intakes. 2 of the 6" passive intakes in the grow tent are the exhaust of the clone/mother tent. The third 6" passive intake of the grow tent intakes just pulls from directly behind it. The mother/clone tent has 1x 6" passive intake and there is plenty of suction in there. I hooked up tassels to the intake vent and a web cam and I can see them blowing real good. The temps never go more then 5*F above ambient in the mother/clone tent (I actually think my thermometer is inaccurate and the temps are at ambient... I'll have to get some more to check).

    This helped a bit and the sticky isn't being pulled off of the Velcro and zippers now. The tent is still being sucked in quite a bit, so there is quite a bit of vacuum. I think it is more than the clone/mother tent because there is less PVC per square foot of tent area (less bracing). I'll add some more bracing 12" above the top of the pots... this will also be where the scrog screen rests on... 2 birds. I'll also add some more near the top of the tent. I got inside and pushed out on the panda film at those heights and it made a huge difference.

    Thanks all.

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