Dehumidifier problems

I am having issues with my humidity and dehumidifier in my 5x5 tent for 2 days now I been fighting this ongoing issues I am at lost ends don’t know what to do anymore. I have tried every thing that I can think of with no luck at all. I have good air flow but as I watch the humidity go up then the dehumidifier kicks on the humidity raises to about 55-60% I have my inkbird humidity controller set to 42% temps. set to 76-78F. As I watch the humidity raise and the dehumidifier controller kick on it raises to 55-60% then drops down to set point to 42% then it stays like that for about 2 minutes then it raises again it has been ongoing for the last 2 days after watering/feeding them.i have a diagram of my tent and a screen shot of the graph any help on this is much appreciated.


Hey buddy
Humidity can be hard to control. When it rains here my humidity just goes up!
I have the ink bird humidity and temp controllers also. Is your inkbird humidity probe right next to your pulse?
I had to calibrate my inkbird to match the pulse as it was anywhere up2 10% different.
What is your humidity differential set to on the ink bird? I struggle to dial in humidity to. And as the plants get bigger it changes through the grow!

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Also make sure the exhaust of your dehumidifier is not pointing towards your probes. The ink bird probe is so sensitive my experience is it will change from just u blowing on it. The ink bird changes much faster than the pulse. I used the box my pulse came in. Cut some vent holes in it and have my inkbird probe and the pulse in the box like a shroud. Seems to level the reading out a bit. Never give up!

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Hey buddy I noticed w the InkBird controller that when it kicks on the dehu the dehu doesn’t kick right into dehu mode. It does a cycleing thing to I think get a proper reading before it kicks the compressor on. That’s one reason I don’t use the InkBird on my dehu. It delays the compressor too long for how I like my room to run. When it isn’t being “de powered” it keeps everything way tighter for me. I did notice also my dehu is 5% off from the pulse in my grow so I adjust accordingly.

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Everything it dialed in and I calibrated after a full 25 hrs. The humidity differential is set at 2. Yes they are by each other. Now the exhaust fans probe is a mid- high of canopy. Yes the humidity probe for the inkbird is very sensitive. I try not to fight humidity but as they get bigger like you said they need more water/feeding then they soak up the water fast now how I water is I get the top 3-4 inches of soil wet then wait 20 minutes then I finish watering them. But after doing some changes to the numbers it seems that it’s slowly stable right now hopefully nothing goes wrong but we both know how things can change of a fly with dealing with humidity. Thank you for the advice.

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Ok I see now this is why when it kicks on the humidity still raises then after a while the humidity goes dow, that makes sense now that you said that. So should I have the dehumidifier not plugged in the controller? In that case it would run all the time, now the dehumidifier that I have it has a fan that runs constantly would that be a problem? Have not tried that yet maybe I should to see if that changes the humidity problem that I am having

As long as your compressor isn’t constantly running it shouldnt be a problem for the fan to always run. It’s barely any energy for the fan alone. I would give it a try and see how it goes. I would also keep an eye on your dehu set point and make sure that the humidistat 55% is actually 55% on the pulse . I have to set my dehu at 60 to keep my RH at 56 . And I noticed my dehu seems to work better on low than high in my setup.

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Yes, I am trying this as we are speaking now I’ll give it a couple of hrs of running at 60% it check it, hopefully this will work I am running out of options and they are in flowering so I don’t want to ruin it because of a humidity problem. The running on low is something that I didn’t think of so thank you I appreciate it :facepunch:

In my inkbird humidity controller there is a dehumidification delay setting. Which iv set to zero. So when it hits my target it’s on. I have the wifi model. If u have the same the setting should be there.

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I do have one, well I have both that are wi-fi and the humidity is set to 2.0, actually the both of them are set at 2. Everything so far are at stable conditions right now so I am keeping figures crossed :crossed_fingers: and hope they stay stable, until the next watering/feeding this is when i start having issues :crossed_fingers:

Wifi is awesome u can check and adjust on the run
I’m not meaning the differential set at 2.
On mine there is a humidity delay. Which delays the dehum from starting for a set ammount of minutes. 2nd from bottom option on mine !


Dont know if my screen shot worked.

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ok I see what your talking about now, it has Pt its set to 2 also
and the screen shot did not come through
@Moderndayalchemy had a suggestion about not having the dehumidifier hooked up to the controller and so I unplugged it from the controller and i did had to set at 55 to have RH at 45 RH so thank you both, I really appreciated you both
As you can see it was jumping all over, so about 8:30PM that’s when it got stable and so for so good

Just out of curiosity are those highs n lows when your interrupting the environment? Anytime the a vent is opened or a Velcro window or zipper it’s gonna go haywire for a few hours? It tough to wrestle the environment inside a tent. For humidity I’ve always used exhaust to better control it. If your feeding your plants properly they are gonna give you all the humidity you can handle through transpiration. I put furnace filters over all lower openings and leave them open and use ac infinity to control RH and dimmer on my lights to control temp. Works pretty well for my liking.

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I would close any intake air at the top of the tent. Put your intakes at the bottom. My thinking is your pulling air from the bottom and the top sandwiching the air at canopy level could be causing your micro climates?🤷🏼

Yeah I had the tent opened for a couple of hrs doing some leaf tucking and some cleaning and messing with the dehumidifier. I also use furnace filters but didn’t think about putting them in the bottom vents very smart, I have them on the ducting on the intake, I was at Home Depot and saw those floor filters that you put in those vents 2 of those would fit one of the tent vents. :facepunch:

The one ducting on the top left is just a vent to regulate the negative pressure. It’s just ducting that’s it… Do you think I needed it or not…

The 2 at the bottom (intake) is hooked up to the 6” 400 CFM fan that has a splitter with booster fans( they are putting fresh air inside the tent

If you could automate these to turn on only when needed instead of always on it’d prolly tighten your parameters a bit.
Yeah bro after I did my first ever indoor bud wash at the end of my grow I would always recommend filtering every little intake no matter how small and keep strict limits on the amount of time your tent is open. There is so many spores and particles in the air all that shit gets stuck to your flower. It’s actually disgusting when you see how much shit is on ur end product from the air😔

OH yeah…Forgot to mention I have an exhaust build in to the AC/Furnace to my house that I have attached to that exhaust to the roof of the house if you can find that every house should have them and I don’t have to worry about the smell, shit man I heard of people taking dramatic measure and hooking their exhaust to the sewer line… :nauseated_face: :face_vomiting: :exploding_head:

Yeah…I figured out the dehumidifier cutting on and off was the problem and you are correct about opening the tent it does help a lot. and yes after the last grow I use those filters for your home vents work pretty good for my in take and exhaust, I don’t use carbon filters do to it causing your fan to work more from pulling air out of tent. I have a Pitt so yes I occasionally see black hairs on the buds but after using those filters it does a good job from particles coming in.OH and I use those after markets car filters for my exhaust and and dosnt make the fan work hard too.

Nice I like a arsenal of grow hacks at my disposal. I guess you could vent right out of your clean out but if your fan ever cuts off I’d imagine the backdraft would make your weed taste like shit😔 literally haha. I’m gonna look into the furnace thing tho. I currently vent out right next to the dryer vent but I’d love it to go out the roof!

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Yeah…the sewer line I would do or even think of doing. No way in hell. Not all furnaces have it though