what is your rh fluctuation between lights on and lights off?

[GrilledCheeze]

So running daytime in the 55% range, shut the lights off, temps drop, leaves let go of the water they have in them and boom spike.

I have come down in the morning before to water droplets all over the inside of the tent. That's a problem. I run sealed with CO2, which makes it worse.

I've also had this happen and it's scary. Makes me worried about damaged equipment and even fires.

 

[GrilledCheeze]

Our Hvac system has built-in dehumidifier so I set the ambient rh on my t-stat at 40% then use the tent exhaust fan via controller 69 to regulate rh in the tent. I keep it around 45-50% these days(late flower). My day/night temps fluctuate 5 degrees or so but rh stays relatively stable.

That's basically what I'm doing right now with temps being colder outside. At lights off I just unplug my exhaust from the Inkbird temperature controller and plug it into the dehumidify outlet on the humidity controller. I have a tight window set on the %RH range so the fan just burps the tent every 5-10 min which doesn't impact the temperature too much. My system is very manual that way and the changes I make often coincide with the outdoor temperature.

 

[Cool_Beans]

sound like you got things dailed in there, whats the temp in room with everything running or vpd

I have it pretty easy since my tent and new grow closet are in/off my mechanical room, which stays around 75-85f depending how much the furnace is running, so the temp inside the tent stays in that range w leaf temps around 73-75f. Ambient temps closer to the floor are around 70f, so I've been opening or closing flaps depending what I want pulled in. I have been able to maintain 1.1-1.5 vpd through flower, but this is only my 2nd grow so I'm still learning it. My dumb ass realized the controller 69 displays it in the app for you and I dont have to squint at that vpd chart anymore. I'm sort of app adverse lol.
Edit- Here's where it's at right now, I watered them this morning.

 

[Goodshit97]

how do you maintain rh during lights off
how big is your space

Im in a 4x4, i run 4 plants, i water as soon as my lights come on so they have 12 hours before lights off again. Usually only see 7-10% swings when the lights go out. In the spring/summer/fall, i run a 30 pint dehumidifier 24/7 to keep humidity at like 45-50%

My veg tent runs 60-62% consistently, both my tents are exhausted by a t6 ac infinity. Best thing i bought for the grow, made my life so simple.