Humidity swings

[Mad1operator]

Hey all, I ambcurious of anyone else has swings in their rh & if they cause complications. Im in 4x4x6 in a basement, small room. I bought an 800 btu ac and the only issue ive got so far is about an 8 point rise and fall in my rh overnights. Im sure the Missouri weather isnt helping much right now, no consistency. Attached pics of last few nights. Evens out with lights on. I do have filter and exhaust running without an intake fan.

 

[Negrodamus]

You again?!?! Lol jp... Unless you have a sealed off room with a dehumidifier outside the tent, or in the grow room itself, it's really difficult to get rh stable. My humidity sometimes goes as high as 70% and as low as 30% in flower. It is possible to flower with high rh and crazy rh swings.

1. Defoliate/schwazz when you switch to flower, then do it again to the canopy on day 20 of flower. Literally take out all large fan leaves not attached to bud sites. Pic below is the first defoliation I did yesterday after flipping to 12/12, I'll do the canopy in 19 days from now.

2. Box fan in back of tent, small fan on floor blowing up through leaves, and 2 clip on vivosun fans blowing across the top of the canopy.
3. Mini dehumidifier in bottom left corner, and an Eva-Dry hanging from the top.

The main idea is providing MAXIMUM airflow while also decreasing surface area so that mold cannot take root on leaves or buds. I find the mini dehumidifier helps lower my rh about 5-10% which isn't huge, but at least it's something. I live in the great lakes so humidity is always an issue in flower but I've never had mold or pests with that 3 step system outlined above

 

[Driver733]

Yes, the humidity in my 4x4 tent is about 40% with the lights on and will rise to 60% with the lights off, and I am running a dehumidifier in the room the tent is located and draws air. I'm waiting to see how it goes as the weather gets colder, also it depends on how humid is the weather outside.

The funny thing is I bought an extra large dehumidifier, good for a whole house, and works between 30% and 80% humidity. I can run it for 12 hours, the entire time the lights are off, and I can't get below 40% in the room. Seems like it should go lower, but it may have to do with the temperature.

In any case, as long as I remain no higher than 60% with the lights off, it will have to do. It's much better than it was this summer, I have no A/C and got some bud rot due to summertime humidity.

Edit to add: I do pull about a gallon of water from the air in the 12 hours, so it is definitely working, it just won't get the humidity any lower than 40%.

 

[Mad1operator]

You again?!?! Lol jp... Unless you have a sealed off room with a dehumidifier outside the tent, or in the grow room itself, it's really difficult to get rh stable. My humidity sometimes goes as high as 70% and as low as 30% in flower. It is possible to flower with high rh and crazy rh swings.

1. Defoliate/schwazz when you switch to flower, then do it again to the canopy on day 20 of flower. Literally take out all large fan leaves not attached to bud sites. Pic below is the first defoliation I did yesterday after flipping to 12/12, I'll do the canopy in 19 days from now.
View attachment 4724636
2. Box fan in back of tent, small fan on floor blowing up through leaves, and 2 clip on vivosun fans blowing across the top of the canopy.
3. Mini dehumidifier in bottom left corner, and an Eva-Dry hanging from the top.

The main idea is providing MAXIMUM airflow while also decreasing surface area so that mold cannot take root on leaves or buds. I find the mini dehumidifier helps lower my rh about 5-10% which isn't huge, but at least it's something. I live in the great lakes so humidity is always an issue in flower but I've never had mold or pests with that 3 step system outlined above
View attachment 4724646

As before, appreciate your time and advice. I do need to get another fan or two for sure.

 

[Negrodamus]

As before, appreciate your time and advice. I do need to get another fan or two for sure.

As long as your temps and airflow are spot on, an rh of 70-75% lights off, once or twice a week won't be a problem. If it goes over 80% though, that's the danger zone even with 4 fans going strong.

 

[Mad1operator]

As long as your temps and airflow are spot on, an rh of 70-75% lights off, once or twice a week won't be a problem. If it goes over 80% though, that's the danger zone even with 4 fans going strong.

My range is good, my real concern is in the graph, swings are clockwork with the ac coming on and shutting off. So its up and down every 15 minutes or so.