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Lets talk fan / air movement


New Member
I have some questions on air movement. First off, do the fans need to be on 24 hours a day all the time? If not, how long do they need to be turned off?

I am doing a closet grow and if the fans are not on, then the air is stagnant; could this effect growth in slowing them down? What if I have the fans on, but the door to the closet closed?

Looking for answers from advanced/pro growers... thank you. :peace:


New Member
As long as you can run them each day without causing drying is best. Your stems will grow stronger just like they do in nature with wind blowing them all day, the plants will aspirate better as a whole, and it can also create wind which pests like gnats and such do not like.
Your plant won't simply die without it for 24/7 however. I run some of my fans on the same timer as the HPS more for cooling than anything else, so they may only be on for 12 to 18 per day depending on plant stage. Do what works for you within reason and you will be fine.


Well-Known Member
The fans are not required to be blowing 24/7. the wind doesn't blow 24/7 after all so why should a fan have to? As long as you can control the temps and RH (humidity) is what's truly important. When the babies are small a fan helps strengthen stems but even then a 24/7 regimen isn't needed. The best fan I ever had ran off a environmental controller and had what is known as wind effect. When it was running it varied it's speed to mimic the wind gusting. The environmental controller turns the fans on when temps or humidity gets too high. No fan in my room runs 24/7. It would make controlling RH harder and would dry out my plants more often requiring more nutrients and waterings. Basically it would increase my work schedule unnecessarily.


New Member
Just setting my room up and I have a question regarding fans. I will be running two rooms one veg & one flowering each about 8X12. I got an old central heat unit and am using the squirrel cage to exhaust the one room for flowering. It really moves lots of air. I plan to put a carbon filter on the inlet to destink the exhaust. I wonder if this unit will be too much for my little room. I plan to use window type fans to keep air movement in both rooms but the exhaust unit may take out too much air. What do ya think?
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