RH increasing with lights out

Lights out Rh increases? running led for the first time. lights on room temp is around 78. Rh usually between 38 and 55. When lights are out the temp drops to about 68 and the Rh can get as high as 71. I have never had this problem before. Excellent circulation. this is not a sealed room. what can I do to reduce the humidity when lights go out? When the room is warmer it seems to drop the Rh? Any help would be greatly appreciated.

get a dehumidifier

That's very normal for rh to Increase on lights out. The lights reduce rh. As rm3 said, get a dehumidifier if your concerned.

Personally I wouldn't worry about it getting to 71%. Mine gets up there all the time as its humid as down here. Never had any issues.

If its under the lights that might affect it at lights on, they are best positioned away from the lights or in shade.

I had this issue last year using hps. It was at 80 percent for 2 days I got some mold on my JTR. clipped, washed , sprayed for weeks. Eventually it spread to my blue dreams. Upsetting. Nervous now I'm still running those strains. Funny I have never had these issues before. I haven't changed anything. Maybe I should update my prefilter too. It's on third year but it still eliminates any odor.

I run a dehumidifier if needed when blooming.

You can get a cheap (cheap being a relative term) dehum. from home depot for about $100. But it can be a pain. You have to empty it, gets full quite often depending on size. Being in the HVAC-R industry, I just ordered a whole house dehumidifier. If you can find one for less than 5 or 6 hundred, I would highly recommend. Especially if you live in a humid state like myself.

I have a Dehumidifier the way but I'm so cheap I don't want to use it that often. 320 watts I believe! That's a to of electricity

zman33 said:

I have a Dehumidifier the way but I'm so cheap I don't want to use it that often. 320 watts I believe! That's a to of electricity

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My issue with my dehum was that it made my room insanely warm. Just as hot in lights off with the dehumidifier running as it was when the lights were on. I'm going to run a whole house dehumidifier from the basement to keep out the heat. Electricity shouldnt be too big of an issue for a whole house dehumidifier because it creates a uniform RH in the entire house and shouldn't need to run very often.

papa canna said:

My issue with my dehum was that it made my room insanely warm. Just as hot in lights off with the dehumidifier running as it was when the lights were on. I'm going to run a whole house dehumidifier from the basement to keep out the heat. Electricity shouldnt be too big of an issue for a whole house dehumidifier because it creates a uniform RH in the entire house and shouldn't need to run very often.

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Actually if sized correctly they will run quite a bit plus the furnace fan needs to be tied in so hopefully your furnace has ECM blower. As for OPs question the amount of moisture in the air has probably not changed drastically just the colder air is not able to hold as much so higher "relative" humidity.

When my lights are off my rh goes to 65-75. I run 2 dehumidifers. They bring it down to 45-50 with lights off. Room size 20x12

my controller does this for me and if rh rises it kicks the extraction up but you need to have extractors alot more powerfull than you need to truly benefit on a controller but in my situation it was much better to buy a fan controller than to buy a dehum.
controller cost 70 quid
and it keeps my temps in check and rh i could of got the upgrade so i can wire up a heater too so if temps dropped the heater comes on but i have never needed to warm my tent up so this sounded good but unrealistic for me

I got a 30 pint, not so big. I believe it's automated so I shouldn't have to fool with it that much. Some of you say they get hot? I'm in a 5x4 room, since bloom there is no room left. May have to hang my big fan above the canopy. Would probably get better coverage with it. That would give me the space I need for the dehumidifier.

To everyone who has posted, I really appreciate the feedback.

zman33 said:

I got a 30 pint, not so big. I believe it's automated so I shouldn't have to fool with it that much. Some of you say they get hot? I'm in a 5x4 room, since bloom there is no room left. May have to hang my big fan above the canopy. Would probably get better coverage with it. That would give me the space I need for the dehumidifier.

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They produce heat by their very nature. Cheaper than resistive heat though if you need heat .