Huge humidity problem with lights off 12/12

I am currently indoor tent in the basement fresh air intake and outtake outside. Air movin at all time due to the 1000 hps and heat issue. 12/12 as is
9am-9pm light off
temp 65ish rh 80+
9pm-9am lights on
temp 77-85ish depending if I crack the tent
rh 30-50ish
flowering starting week 2 always water wen lights on first thing and fan never shut off

Sounds like you need a dehumidifier or larger exhaust fan.


You could also try shutting your intake fan off during dark hours.


During dark hours the air cools and RH increases.


As plants get bigger, ie more foliage they transpire more and more vegetation means more moisture within the air.


J

do u have anything in to tent that increases the RH.(bowl or cups of water)

i basically have the same situation.

after lights go out my exhaust fan will run for another 1/2 hour, then my dehumidifier comes on. then it shuts off about 1/2 hour before lights on and fan comes on.

the later i get into flowering the more i worry about the humidity.

An option for you would be to change the light on cycle, i run my lights at night because power is cheaper and because it helps to keep temps in check in the day with out having to run an ac, but you could bennifit from this because the temprature would not drop so much inside the cab when it cools off at night so you would not have such high humidity...

I have to run my out take because of stealth issue. It has natural airflow as it is thru the chimney. Keep ls negative pressure in the tent and small away from house period lol.

My logic is as follows correct me if thinking wrong:
Natural day time warmer then night and humidity is lower correct? So I run my lights at night because the cool night keeps temp and humidity right where I want it. Thats all good. Its lights out at 9am thats raises the shit out of my rh. I have plenty air flow just can't combat the lights off humidity

Also damp rid seems to be helping .....

Sounds like you are at least following a schedule...many do not. I run my tent lights all night too. Remember that these plants are made to tolerate heat and humidity. My tent fans and exhaust fans NEVER go off. It has been in the low 90's here for the past week and my girls are flowering just fine. Also, when it is very hot, I cut back on the nute solution and every other feed is tested water only. Good luck. Peace...

Bird dog awesome and thanks. Max temp is 86 and they love it tbh. Can't see mold and mildew with filters and fans running nonstop

What strain ? And my grow is bagseed so hoping they can take some abuse ( and they have )

Inbox is full birddog lol

Sorry dude...try again, as I cleaned it up. I get lots of messages.

The one and only solution for your humidity problem is a portable dehumidifier.

SmokeMe420 said:

My logic is as follows correct me if thinking wrong:
Natural day time warmer then night and humidity is lower correct? So I run my lights at night because the cool night keeps temp and humidity right where I want it. Thats all good. Its lights out at 9am thats raises the shit out of my rh. I have plenty air flow just can't combat the lights off humidity

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i also run lights at night to combat the heat.

the dehumidifier will also raise the temp. in the room, so you need to watch that when running it. and you can't run the exhaust or it is just fighting the dehumidifier.

i have plenty of air movement and never have mold, but i have had budrot due to high temps and high r/h.

this year i had a high r/h but the temps were cooler allowing me to run the dehumidifer.



are you getting your intake air from outside like i do?

I actually was wondering how to combat high humidity during lights off as well. For anyone who can help, my rooms 1.6x1.8' and atm I got one 65w and 55w CFL running. Lights on 6pm-12pm. With lights on, temps are 75-82F~ with RH 50-60~. Lights off I believe humidity gets up to 75~. During flowering is that guaranteed bud rot? I'm looking into extra small dehumidifiers, but having trouble finding ones within reasonable price. Oh as for fans, I have one case fan blowing air in at 45cfm, and S&P TD100 attached to 4x8 phresh pulling 100~ and I have another 45cfm case fan helping my S&P out. One 5" O2 fan for ciruclation. Fans run 24/7. If I get a dehumidifier do I need to turn the exhaust off during lights off? What about passive intake? (Both my case fans are wired to one converter, so I'd have to rewire the fans and find another converter =T). The actual room the cab is in I believe humidity is between 60-70%. Thanks in advance, and sorry didn't mean to jack the thread in anyway...

I too have a basement grow. Lights on at 8pm. Humidity is anywhere from 70-80% at this time of year. I was worried at first, but have come to realize that as long as you have a constant flow of air on your canopy (especially during lights out) then u really should have nothing to worry about. I have a passive intake, i keep my outtake on 24/7, and have a 36" tower fan ocilating at canopy level 24/7. I have colas the girth of a pop can and i inspect them daily. I have absolutely NO signs of mold at all.

amgprb said:

I too have a basement grow. Lights on at 8pm. Humidity is anywhere from 70-80% at this time of year. I was worried at first, but have come to realize that as long as you have a constant flow of air on your canopy (especially during lights out) then u really should have nothing to worry about. I have a passive intake, i keep my outtake on 24/7, and have a 36" tower fan ocilating at canopy level 24/7. I have colas the girth of a pop can and i inspect them daily. I have absolutely NO signs of mold at all.

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Ok, thats nice to know. Lights off, I haven't been able to check the humidity highs and lows on my thermometer lol... have to figure that out. But I know it must be around 70% with lights off, cause the basements humidity is around 65-72 ish. But I do have ALL my fans running 24/7. Two case fans, one exhaust, and one O2 5" fan just for circulation. Should be good with the mold?

treegoesmoo said:

Ok, thats nice to know. Lights off, I haven't been able to check the humidity highs and lows on my thermometer lol... have to figure that out. But I know it must be around 70% with lights off, cause the basements humidity is around 65-72 ish. But I do have ALL my fans running 24/7. Two case fans, one exhaust, and one O2 5" fan just for circulation. Should be good with the mold?

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Im thinking so. I check daily and still have had no issues, i would just keep a close eye on them. I picked up a digital hygrometer (weather station) from walmart for $7. It tells u current temp, and tells you your lowest & highest in the past 24 hours. It also does the same for humidity. Might want to grab one, this way you can see where your humidity peaked at during lights out.