humidity in grow tent

[marpolo]

in the flowering cycle no problems with humidity during day cycle, stays around 40-45 %, night when the lights go off it rises to 55- 64 %. i have two small dehumidifiers in my tent 4x4x80. why do humidity levels go up when lights are out? another 3 weeks I'll need to be between 35- 40 % for end of flowering cycle. bigger dehumidifier? no exhaust set up, would that help? only have a 300 w LED and a 150 W HPS in tent. thanks for any help in this matter...

[Weed Pharma]

The humidity goes up because the temperature goes down during the dark cycle. Yes an exhaust set up will help.

[marpolo]

thanks man. intake in or out of tent?

[Pyro1711]

Both...pull cool air in and push the air out through a vent to outside or through a carbon filter for the smell

[Flockshot]

Warm air will hold more moisture than cooler air.

Lets say that a room that is 80 degrees F, can hold 2 quarts of water

If is has 1 quart of water evaporated in the room, it is at 50% of the water it can hold, so there is 50% humidity.

When that same room full of air cools to 65 degrees F, the room can only hold 1 1/2 quarts of water evaporated into the air.

It still has 1 quart of water evaporated into the air, but that one quart now represents 66% of the maximum the air can hold and therefore reads 66% humidity.

Your humidity numbers are all good, by the way.

[Flockshot]

The thing for me is that I am not committing to the perfect environment.
I consider myself a average hobby grower at .66 grams per watt on my light.
If I am going to spend a bunch of money to control more than that, I want go get that back in my harvest, or I won't do it.
As it is I need dehumidifier in flower, but that is just to survive in the summer, and I will not use it when I don't need to for mold protection.
I see crazy claims on this site of 1.25 grams per watt but I don't believe them, so I just grow along at my .66 and wait for something cost effective that will be the next big deal.
I started out studying everything I could get my hands on, and learning the science. All I found was false claims so now I grow, smoke, repeat.
I do enjoy learning what the science guys are studying currently, but my belief is that I don't think it makes a lot of difference.

[Flockshot]

That's great. You are doing really good.

[marpolo]

thank you all for your help. much needed!!

[marpolo]

temps are running between 70 and 80 degrees pretty steady on that

[marpolo]

thanks again man! my first grow , looking forward to the end of this cycle. just planted two auto seeds yesterday..looking for a shorter period of grow time. they seem to be a totally different
style when it comes to them. any pointers on those . appreciated as well!!

[marpolo]

my VPD according to chart is around 1.3. that a good place to be? that's an average i range from 40 % RH - 64% RH . temps stay between 72 degrees - 80. days closer to 40 nights closer to 60 % RH. and thanks for the auto info also. can and do you recommend using lights or outside for the auto flowers. or a little of both??

[marpolo]

i have six seeds ,I'll try both ways and see which one comes out best. I can get 6-7 hours of direct sunlight every day. will be fun to watch the difference. thanks again..

[marpolo]

first go round at this, enjoying the hell out of it!! never knew about VPD. will def keep an eye on that...

[marpolo]

at my age , perfect hobby for me. I'll turn 59 next week.. just what I needed to relax ..

[Pyro1711]

Lol... I thought VPD was a STD.... When you start your autos... Keep them under 24 hour light for about the first month... I start my seeds in Rapid Rooters after they pop, then I keep them warm in a humidity dome until I see the sprout starting then I throw them under my cheap ass $15 Amazon special 50w LED light that is a circular disk shape, I wrap the light with a towel... Couple of chip clips to keep the towel closed.. once I see some root start to show through the rapid rooters, I sink them into my soil mix in these cheap plastic pots I got from the dollar store. Once they get going I then put them into their final pot. But I really think that the 24 hour light at first really jump starts them. And I definitely put my autos outside whenever I can.

[marpolo]

makes sense, and have the tents for that purpose. thanks man!!