At night, or actually day, when the light is off I'm getting about 57% humidity. Temp no lower than 66F for flower that's too high yea? I have a 36 cubic foot closet. What size dehumidifier do I need? And I'm sure I'll only need to run it while the light is off. While the light is on its got to 83 but im trying to bring that down. With more ventilation. Hard to keep the temp steady tho. How important is that while light is on. Humidity seems fine tho with light on
Here's a "Vapor Pressure Deficit" chart that tells what the optimal humidity range is for any given temperature (Green=Good; Yellow=JustOK; Red=Avoid): I like ultrasonic, top fill, cool mist humidifiers, and after several tries, I settled on this one: I seem unable to post the amazon link, but my humidifier is a Honeywell Top Fill Cool Mist Humidifier, Model HUL570 series. Top fill is a must for me.
if i were you i would vent the room out with a small fan it will suck out that nasty air and pull new air in wich is better to bring co2 and prevent molds . just throwing a dehumidifier in there will work but will not give the best results small area
An exhaust fan is almost always necessary for an enclosed system. The speed of that fan has a large effect on humidity, and a smaller effect on temperature, so a cheap motor speed controller is needed.
If it's too powerful of exhaust it will increase humidity? I think that's what's happening. Is 51% at 69f too much humidity at night for flower? Lights on humidity goes down to the 30's
I follow the VPD chart guidelines given above. Objects inside the tent/room can store lots of heat, but no humidity. If you turn the exhaust fan on full blast, it will quickly remove the humidity, but only remove the heat slowly. Two things can increase humidity: (1) turn up the humidifier (2) slow down the exhaust fan. My opinion is that if you have breezy air movement inside the tent, then with hydro especially, there's little chance of bud rot, no matter what the humidity.
65% RH is ok for 80 F. Some of the VPD articles recommend different values for different life stages, but that's probably unnecessary. The VPD chart was developed by academic scientists to maximize plant growth by making sure that the roots take in, and the leaves and expel, water with minimum plant stress. It flies in the face of seat-of-the-pants, unproved, conventional MJ growing advice. Some commercial growers ignore the conventional wisdom, and are taking advantage of VPD to produce faster, bigger harvests. People using VPD report no bud rot issues.
K well I've been in my 30 and 40 at 80f. Except when I run tr he humidifier. But then humidity gets to 70 with the lights off.. I guess I need to run the humidity at light and a dehumidifier at dark?
You'll need to figure out day/night heater/humidifier/exhaust settings thru trial and error. Since the same air has higher humidity at lower temperature, and the plants themselves produce some humidity, you should be ok at night without any dehumidifier or humidifier, but might need a heater. Those VPD chart values are just guidelines.
Alright yea. Ha. I just put a little space heater in a few hours ago. Well see . Humidity was getting up to 58% 70f I'm just switching to flower