Ventilation humidity problem

I have a 5x5 grow tent and a 3x3 grow tent. Having a huge problem with humidity. can I exhaust the 3x3 into the intake on the 5x5 , through the carbon filter back out the 5x5 out the window?.. does this sound crazy or will it work?

Depends on what issues your having with humidity…
High or low etc etc…

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Yes its will work…

It will work, most likely to lower RH since you’ll be intaking warmer air from the tent than would be in the room because of lights.

I promise that link wasnt intentional

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Sorry… the rh is way too high I’m 2nd week flower… and the humidity is around 68%when the light is on…and 80% when it’s off…

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Yeah you definitely wanna get that down. If your plan doesn’t work try DampRid from Lowe’s or Amazon. It’s what I use. It absorbs moisture out of the air.

I put 1 damprid inside of the 5x5 couldn’t tell much difference…how many do you think I should buy…the room the tents are in is 10x10 … thanks

Not sure exactly. I used one in my 30"x30" before I went to 4x4. It may not be enough for your situation. If your plan doesn’t work you may have to buy a dehumidifier.

@RandomlyRan I know this is an older thread but I’m growing in a 2x4 tent. I had 3 plants but 2 ended up being males so got rid of those. I have a similar dehumidifier and another from amazon and both in the tent but humidity is still around 60+. Does your dehumidifier keep the humidity down??

It’s hard to keep it down when it’s drawing in new air every second. May need one large enough for the room that the tent is in so the fresh air that comes in is lower rh

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Also my tent has 3 flap vents on the bottom. I have one opened and have 6 inch duct one one side and a 4 inch duct on the opposite side letting air in and a 4 inch exhaust fan. Tent is in a bedroom need a window. Have exhaust blowing out towards the window but vents are letting air in from room. I’ll take a pic of the setup when I’m home from work to get your guys opinion.

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My dehum worked but my fan was adjustable so I wasn’t sucking more air in than I needed. I slowly turned it up til I saw gently neg pressure. You can buy fan speed controllers on amazon. The heat from the light should remove some rh. I also used a damprid bucket. Also if your extra bushy you can defol lower fans that push into each other. Foliage stacking is a water and rot trap. Just based in reading this I would;
Remove the 6" duct
(Ideally same diameter in and out and if one is bigger it should always be exhaust)
Cover the end of the 4" tube with pantyhose
(Bugs and it slows the intake process slightly)
Defol where needed
If that doesn’t work you can consider adjusting your room as a whole, as mentioned by @Painfree,and use your room as a lung room or buy another small dehumidifier in the tent, as its cheaper. I’m in favor of controls. I’m building a control panel with all my drivers and fan controllers and inkbirds I’m saving up for.


I’m not in need of my small one anymore. If your on the lab I can get your info and mail you mine. Lol. I just built this room. It’s a little over 5’x15’ @Gremmall

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This is 2 weeks ago when I got my new light. The set up is still the same as the pic except only one plant is in there with a trellis net. The 6 inch duct is on the left n 4 inch on the left by little clip fan. I’ll go ahead and remove the 6 inch duct and see how it does.

Removed the 6 inch duct. Humidity is at 50% when I got home. I switched the light cycle to flower last week. Just fed her today but saw a few fan leaves rusting n yellowing. 2 fan leaves shriveled up completely so I’m guessing I have to feed her everyday as before I was feeding her every second day.

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Do you use calmag? Usually if it’s rusty (Cal) and yellowing (mag)

Yes I am. I’m using 5mL per gallon of cal mag sometimes 7.5mL