Grow Tent Ventilation (Help please)

Discussion in 'Grow Room Design/Setup' started by Stiller, Mar 5, 2015.

  1. #1 Stiller, Mar 5, 2015
    Last edited by a moderator: Mar 5, 2015
    Grow Tent
    I have a 5'W x 2'L x 8'H  grow tent made of 1/2" PVC & panda film.
     
    Centrifugal Fans
    I have a 6" 120W (435 cfm) fan, along with a 4" 60W (120 cfm) fan.
     
    Lighting
    1,000W 6" MH/HPS light housing/ballast system. (Currently running MH for veg)
     
    Intake
    6" Hole at the bottom connected to a 6" aluminum T joint. (Box fan inside next to hole)
     
    Circulation
    Small 9" fan inside
     
    Issues?
    The 6" 435cfm exhaust fan is too powerful & sucks in the tent too much,
    The 4" 120cfm exhaust fan is a good amount of negative pressure (combined with box fan), but I think the 1000W lighting is too hot for a 4" 120cfm fan, which temperatures may rise too much?
     
    The tent temp currently sits around 86F at 74F room temp with the 4" exhaust fan.
     
     
    Questions
    - Would I need to get a controller for my 6" fan and just use that as an exhaust?
     
    - I plan on ordering a cheap 6" scrubber soon for odor (in-stores WAY too expensive & big).  Where should I place the scrubber?
     
    - Which setup should I use out of (Plan A/Plan B?) are they good designs? What would you suggest otherwise with the equipment I have?
     
     
     
     
     
     
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  2. What about simply making a second intake on the other end so things don't suck in as much from the 6" fan?
     
  3. If you invest in another fan, I suggest a 15" wall fan for circulation. Much better than the tiny fan or the box fan.
     
    The part of the diagram in plan A where it shows the light being cooled separate from the tent... that style is for an enclosed hood... do you have that?
     
  4. Yes, it's a swing-door glass style hood, so not a perfect seal I'd imagine.
     
  5. Yeah, the Plan B diagram you see is what you are describing. I just don't want to cut big holes in the tent =/ I'm unsure if it will even solve the problem.
     
  6. Anyone have any more ideas?
    Sorry for the impatience, I'm just waiting for more opinions before I begin to cut any more holes in the film.
     
  7. #7 smokeymcdoodles, Mar 5, 2015
    Last edited by a moderator: Mar 5, 2015
    86 is not hot for a thousand in 10 feet. Looks good man cool the light seperatly i agree
     
  8. So you would recommend plan A?
     
  9. Go with plan A. Push air threw your cooled hood and vent the tent separate from the light. If the temps are still to high as stated add a fan at the top of the canopy to move more air in the room around its harder to heat moving air over stagnate air.  As for your air intake try to spread it out even around the bottom of the room so you draw air from all sides instead of one place, this will get more air to more plants. unless your not running a neg setup and your feed air in with a fan.
     
  10. Insulated ducting in and out of the tent all the way out of your room will probably lower your temp 2 or 3 degrees. 
     
  11. #11 Stiller, Mar 7, 2015
    Last edited by a moderator: Mar 7, 2015
     
     
    Alright, it's all done. Problem is that the hood is leaking air. The 6" fan is blowing hard & I can feel air coming out of the sides of the light hood. How do I make a tighter seal? I think it already has a soft white gasket but it's not working. It's a swing-glass tightening latch-style vent hood. Made by sunleaves I think.
     
    Anyway, my temp is at 76 ambient & 86 in the tent (Still same high temp).  I also raised the light about 1 more ft.
    Except this time I am not using the box fan to circulate air, but a small weak one. (box fan uses 200watts - too much wattage for a fan, considering I am already using 200 just for both centrifugal fans).
     
    So questions:
     
    - How do I make a tight seal in the hood while still being able to easily open/close the glass swing door? 
     
    - What type of fan is good to use for circulation & consumes low amounts of power?
     
    - My 6" Centrifugal fan is very loud with the suction, how do I quiet it down? With a speed controller? What kind would you recommend that is cheap & easy to install? Will a speed controller help lower power usage?
     
  12. Also, is my 120-125 4" cfm fan good enough for a 5x2x8 (80 cft.) if I add a carbon filter on it? (- ~20%)
    Or should I swap my 6" (435cfm) fan with my 4" fan & do it that way?
    [435cfm intake w/carbon filter & controller & 4" 125cfm fan blowing through vent light hood]
     
  13. #13 hemptation420, Mar 7, 2015
    Last edited by a moderator: Mar 7, 2015
    My hood isnt 100% sealed either, just a piece of glass that slides in and out its more then enough stop the heat tho, I Also use a 6" 425 CFM on my hood its a monster. normally runs at 104F with no cooling inside the hood and 84 with the fan and slight leaks, ill take the 20 degree difference. If your super worried about the space and air leaking out i would just use anything non flammable to fill a bit of the space so u can screw it closed tighter.
     
    For circulation i just use wal mart fans. Either wall mount or cheapy 19$( i use these as you can buy 2:1 over most other fans) standing ones and i don't put the stands and just wall mount them or throw a ratchet rope on them. Super cheap, dosn't hurt my feelings when one dies from being on for 300 days straight. and they work just as good as any other fan. just get ones that fit your room i think they go down to 12" or 14" and up to 19" or 20".
     
    when in comes to changing air in the room from what i've read your goal is to swap it 4 or 5 times a min. to keep moisture down and also bring in new air for the plants to feed off, also helps with heat. So (LxWxH) x 4. so 80 x 4 = 320 CFM would be your minimum target for your exhaust fan without a carbon filter. i would suggest using the smaller fan on your light if it can handle cooling it or get a bigger exhaust fan.
     
    thats just my opinion dosnt mean its right :D
     
  14. #14 killset, Mar 9, 2015
    Last edited by a moderator: Mar 9, 2015
    Get a speed controller for the 6" fan. That 4" isn't big enough on its own. Speed controller will solve both noise and excessive sucking in of the tent. I have a 6" 440 cfm fan w/ speed controller in a 2'x4'x5'. Usually runs about half way turned down. So its roughly turning the air over 5 times a minute or so. Gives me some room to play with if needed for temp control. I wouldn't want anything smaller.
     
  15. Where are you exhausting to? 
     

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