Cfm/ fan help for grow tent

Discussion in 'First Time Marijuana Growers' started by TwoOneSix, Apr 1, 2016.

  1. Hey everyone, doing my first grow with a grow tent. She's 2x2x3, got it from a friend for a good price. So, the tent has a 5 inch circle vent on top, and one right next to it on the back part that is a 3". At the bottom of the tent there are large screen vents (that let out a lot of light) for passive intake I'm guessing. I have a 4" 100 cfm booster fan for an exhaust and have a 300w Mars hydro LED. Doing a small DWC grow. The problem I'm having is my temps get very high, and escalate quick within the tent. I keep the two screen vents open but am wary about that as it lets out a lot of light, yet it barley makes a difference. I have a 6" clip fan inside to circulate the air at the bottom. When I put my hand near the screen vents it feels as if it's pushing air more than sucking in. My fan seems weak but it's a good size for the tent I have as its a 2x2x3 tent with a 100 cfm exhaust. Any suggestions? Bigger exhaust, booster fan for intake , etc. anything helps cause I'm baffled . Ordered a 4" 165cfm inline fan with a controller made for the fan, if I were to lower the speed on the new fan would that still be too much for the little tent? Do I need to get a small intake fan? Trying to stay with passive intake without letting out too much light. Will post pictures tonight.
  2. It sounds to me like you definitely are going to have to go with a larger inline fan to move the heat out of the tent. Any time you're dealing with a space that small, you're going to have heat issues. Even LED's put out some heat in a small space like that. I would get as much air going inside the tent as possible just to move air around the plants. You're not going to hurt them by throwing some good strong air in there. It actually works sort of like an exerciser to them to help strengthen them up. But the main thing is pulling that heat out of there. If you get to the mid 80's and up, you're risking damage to the plants. Definitely go larger than a clip fan and get the larger in line fan going and hopefully that will help. TWW
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  3. That's a duct booster and you aren't getting anywhere near 100 cfms.

    It's rated for 100 cfms, they're meant for boosting air that's already moving at the weak end of a forced air system.

    Don't sweat it, I wasted money on one too. Returned it the same day though. What you want is a 4" 160-200 cfm inline fan, with a Mars 300 that should bring it down within a few degrees of room temp. I use the same fan with a 250w hps. Cheapest is around $60

    edit: here we go with the new format deleting links, just google 4" inline fan
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  4. #4 Robbie714, Apr 1, 2016
    Last edited: Apr 1, 2016
    I have an Apollo tent 36x20x62 I have an Apollo 4" inline cf 190 CFMs I have a 4" booster fan 100 CFMs and a 4" clip fan and a 6" clip on. My Booster fan is plenty for my tent. I would run your lights during the coolest part of the day which is most likely at nighttime! When you have your fans set up I would keep them on when your lights are off unless you're running them 24/0 I just run my booster fan and in-line fan when the lights are out. You don't want it to be hot in your tent when you first put on your light. And my temps with the lights off are 65° to 70° with lights on 73° to 78° after I got it dialed in correctly. The highest my temps go 82°! You're going to need a 4 inch in-line carbon filter. Or you're going to have a strong smell in your house! and your temps won't get much lower if you're only using a booster fan. You could get a 4 inch booster fan anywhere from $60 to $120 I use an Apollo with speed control, It's anyways been on low unless it's very hot out. I'm sure people on here will help you! Good luck with your Grow![​IMG][​IMG]

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  5. Thanks a lot for the replies everyone, really made me look into a new fan. Just purchased a active air 4" 165 cfm inline with a speed controller so I'll hopefully be able to control the temp better, and if it's too much cfm I can lower the controller and put some 90 degree bends in the ducting to reduce the cfm a little. And @Robbie714 is your booster acting as an active intake? Or are both your booster and inline fans exhausting? I wanna see if giving a little bit of fresh air from outside through the booster into the tent will bring down the temps without screwing up the pressure.
  6. That's another one of my worries is those large vents at the bottom of the tent along the sides let out ALOT of light, but those vents are my only option for passive intake as I only have a 3" and 5" circle vent for ducting and fans
  7. #7 Robbie714, Apr 1, 2016
    Last edited: Apr 1, 2016
    @TwoOneSix I use my booster fan for intake into my tent. I put it in my window only when my temps get to about 80° which they hardly ever do but it's going to start getting hotter where I live. But to answer your question no my booster fan is just for fresh air intake, and intake from my central air I could connect the ducking right to my central air vent. Btw: you won't have to put bends in your ducking bud! Why would you do that that takes a lot of CFM's away! especially the more bends it has the worse it is. Try not to have any Bends with your ducking! My tent is 100% sealed except for the tiny bit of light that may get out. I don't use my passive intake vents I keep them sealed along with all my ports and the ports where you run your wires and electrical. A lot of people I see run there passive intake vents open. My temperatures stay lower with my vents and ports sealed, because I tried it both ways. but what may work for me may not work for you vice versa! To me it seems like you're on the right track so far! I think the key is readingYou'll get more feedback about not to put no bends in your duck work! I'm really a beginner or so try to get another opinion but I know for a fact you can't put Bends in your duck work[​IMG]into my tent I'll send you some pictures if that gives you a few ideas. Good luck with your grow[​IMG][​IMG][​IMG][​IMG]

    Sent from my iPhone using Grasscity Forum mobile app[​IMG][​IMG]
  8. someone recommended this to me:

    i know it is a bit expensive but i think along with an exhaust fan i pulled out a bathroom i remodeled several years ago (and saved for this very purpose) i can create sort of flow through system of intake fan into tent (or mylar film on the walls i want to maximize my space and height...the closest tent i found would fit is the exact one you're using the 36x20x62 but my closet is 44x24x80 or so...i din't want to lose out on yield, i can cut all the holes in my walls i want) so i digressed. it would go:

    INLINE FAN-->TENT--->CARBONFILTER--->EXHAUSTFAN--->out the ceiling into the attic carbon filtered and smell-less... plus i'll probably throw in a oscillating fan to keep em movin movin.
  9. I feel like this is one of those areas you don't want to skimp out in...especially if you're in a less than friendly state and smell is an issue. plus i know plants love air flow.
  10. Sweet, those pics really helped a lot, I'm gonna try both ways: closing the passive intake vents and running duct through the smaller vent with a 4" 100 cfm booster, and a 4" 165 cfm inline as an exhaust with a controller to slow her down a tad. Maybe even keeping one passive vent halfway/fully open. About how big is your tent? I'm only working with a 2x2x3 grow tent so idk if that much cfm would be like a vacuum lol.
  11. It's 36x20x62 but my closet is 5x2x8. Is that all the room you have to work with? TOS

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  12. Yes, for now at least sadly. I plan on getting a much bigger tent in the near future.
  13. I just ordered that AH carbon filter / fan setup (the 6" version) and while I don't know how the filter works I can tell you the fan is very powerful on even the lowest setting. I have a booster fan that doesn't even compare in power. In a few weeks hopefully I can have more information on the filter itself. From first impressions though it seems very well made and VERY heavy.
  14. Just planted her into the dwc, she looks abit droopy to me any ideas? image.jpeg

    Attached Files:

  15. Can add more if need, 2nd pic shows the stem a little better
  16. My fan/filter arrived yesterday. That filter is huge. Should be the last fan and filter I need for awhile even when I get a bigger space. Painted today (Kilz2) and now it's time to cut some holes.

    I was going to put an air intake in the floor with an air filter and like AC vent covering it and then on the opposite side in the ceiling mount the carbon filter that runs into the inline fan that's in the actual attic.

    Sucking nice clean air across my plants, filtering the air and sucking it out into the attic

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