Hundity levels high when light cycle is off

Humidity in my 2x4 grow tent is reaching 55-58 % when my lights are off and plants are resting. They just entered flower so im thinking I could be in trouble as far as mold/mildew and overall hurting my plants. Tent runs low 40 range during the day with the lights on. Whats my best course of action? Is there a small dehumidifier for a 2x4 tent thats effective enough?

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Thats really not too bad.
I have the same thing but get up in the 60s.
Try to keep the air moving well and you should be fine.

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Ok thanks does anyone recommend a smaller unit that would be efficient in a 2x4?

A dehumidifier will have to be in the room itself, not the tent. As airflow in the tent and temperatures will render a small unit ineffective inside a tent and it will only make the tent hotter. Home air conditioning will remove moisture if run a little more. I really think your numbers are ok with air moving.
I harvested a grow that was routinely in the 70s and had just a couple small issues.

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Ok thanks again ill keep a eye on it

Agree with @Spiney_norman . My tent is always between 50% and 70%, and I’m about 7 weeks since flip. As long as you have air movement around your plants, should be ok.
Temps of low 40’s with lights on…what are they at night when lights are off? I’d be worried about the low temperatures more than the high humidity.

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Sorry i should have been clearer about that. Temps at night when resting lights off 67-73 humdity 55-58%. Lights on temps 77-85 depending on ac being direct vented humdity 43-47 range

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You are going to be fine.

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Just make sure your fans run all the time and not just when the lights are on. Id keep them trimmed pretty good as well so air can move freely through the plants.

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I have been dealing with hi humidity all summer which is common where I live. I have 4 fans in my tent and one large isolating fan in the room. My humidity has be as high as 80+%. Lots of air flow is the answer :blush::v:

Sounds good, im still learning what i can i cant trim on these autos.

Humidity spikes when plants sleep and the lights are out. The best course of action is to set you ventilation to trigger at a certain RH, that never hurts because youbwant fresh air exchange as often as possible anyway. As your plants get bigger and fill the tent, you will need to ventilate more frequently. Its just a normal thing.

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If you have a lot of air flow in ur tent u shouldnt have a mold problem and u will find ur humidity is going up because of medium is wet or damp and if u have trays under ur pots make sure there empty cause that will cause ur humidity to go up aswell