How do you keep humidity down in a small tent or closet

Any suggestions for keeping the humidity down in a closet during lights out. It’s ranging from about 75 to 80 when lights are out. Do the small dehumidifiers work?

Increasing airflow can help quite a bit. A dehumidifier if necessary.

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The small dehumidifiers do not work. Need at least a 30 pt. If it’s not humid outside the closet you just need a fan.

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I personally do find the small dehumidifiers work. Mine dropped my small grow space by 10%


Small one typically don’t work, you’ll need a large one as mentioned need to get some air flowing, small fan would do in a closet, obviously depending on it’s size.

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I went through 3 of them that kept popping up. Would only remove a half cup a day. I also have 32 sq ft of tents tho.

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Be conscious that a dehumidifier will add heat to your grow space.


I’m running a little fan, but it doesn’t help. My buds are starting to fill in (GDP) and I am getting concerned about mold.

What is the humidity level in the rest of the house?

Around 50/55% which is what the closet is with lights on.

Ventilation is your friend… :laughing:


Glad I didn’t order one today. Sounds like the little ones don’t work well. I’ll keep my eyes open for a used bigger one. Thanks.

‘Seein as how’ the humidity level is ok in the rest of the house,a small dehumidifier may help.I know one way you can know for 100% certain… :wink:

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Water, water everywhere

If the environment it’s pulling air from is 50/55 and the grow space is 75/80, you definitely need to move more air through your grow space.

I have a dehumidifier in the tent room and and the tent is always within a couple percent or the room. Overbuilt fan for size of the tent. Lights on, usually the same %. Lights out, usually a couple percent higher in the tent.

It’s up to my dehumidifier to keep the room around where I want the tent to be. You may want to get a dehumidifier for the room to get closer to 40% in the last few weeks of flower. It may be ok at 55% but I’d prefer not to blow 3 months of growing so I pull it down to 40% closer to the end.

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I agree, just trying to figure out what I need to buy to do that.

Need ducting with an inline fan to pull air out of the grow space to another room, attic, out the window… anywhere but the grow space or room it’s in.
Room your grow space is in is referred to as the lung room, environment there determines environment in your grow space. You don’t want to recirculate humidity and not get fresh CO2 so you vent outside your lung room.

Lots of people hear like the AC fan (6 or 8 " depending on grow space size). I went with a little better fan but with no controller but I want mine on 100% of the time anyway.

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Sniff, sniff… salestrolling

I also have a closet grow and was having a humidity issue… with alot of rain these last few weeks. I have the room the cost is in with blacked out curtains so I opened my closet doors and the room door allowing fresh air and the humidity dropped from 61% to 49%. Try it and see if it helps.

Cost I meant closet…lol