Humidity with lights off

When my lights and fans turn off humidity gets up to 80%. When lights and fan on 35%. Do I need to get a dehumidifier or should I try and exchange air with lights off? Or do I even have to worry about humidity when lights are off?

You need to fix this. A range of 35% - 80% RH is no good for ur plants. At 35% they will transpire too much and be trying to conserve moisture and at 80% the stomata will close and not breather/grow. You need a fan that sucks that air straight out of the room.

a seedling mat or ceramic heater to raise temps to daytime levels. its the temp gradient that is the culprit

simply leaving a small fan blow at night will lower it dramatically,not a real huge problem till you get to the late budding stages where rot can start in.but 80 is kinda high mine run around 60 nearing week 5 right now.probably start leaving my carbon scrubber /cooltube run at night now starting to notice the odor as well.not sure i would want to add any heat to a grow room!! as some one stated.

lahadaextranjera said:

You need to fix this. A range of 35% - 80% RH is no good for ur plants. At 35% they will transpire too much and be trying to conserve moisture and at 80% the stomata will close and not breather/grow. You need a fan that sucks that air straight out of the room.

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35% is as low as i have ever seen my air and i got a gas furnace sitting beside my grow, that is dry as hell man. during veg mj thrives in high humidity just don't' want it during late bud stages .