Heat and humidity, down the rabbit hole...

[PuravidaC]

Loving my new grow space and the way I can control climate, however, looks like I still have some tweaking to do. When I started a dry run I found that temps soared and humidity dropped to the 20's. I added a humidifier to get humidity into the 60's for veg and my temps dropped to the mid 70's, with 4" exhaust fan turned down as low as possible. Now that I am in flower I have lowered humidity to the upper 30's and temps have climbed to 80 with exhaust fan full speed. I never knew humidity had such an effect on temps. Bumping humidity up a little to get temps back in the 70's. Now planning to upgrade to a 6" exhaust fan when I need to order a new carbon filter. Hopefully that will be the final piece to the puzzle. Oh what a tangled web we weave when we decide to grow our own!!

[Locrian99]

My understanding is relative humidity is how much moisture the air can hold. Higher temps can hold more moisture, so lower temperatures with the same amount of moisture in the air will have a higher relative humidity. This is what the dew point is and why it’s got to drop to a certain point for fog to form. I’d wonder if the humidity is affecting your temp or the other way around.

[Locrian99]

But I guess you said after the humidifier the temp dropped...

[Potted]

Get yourself a variable speed exhaust fan (more controll) over the environment. Lol

[PuravidaC]

I have a speed control for exhaust fan but it's a 4", 190 cfm fan. When I do the math that should exchange air in grow room 3 to 4 times a minute which was fine for CFL. But I upgraded to a 315 and my grow space is small (2.5' X 3.5' X6.5') so I am thinking I need a bigger exhaust fan. Seems like most folks here run a 6" exhaust fan and have no heat issues with 315's. Seems like I have replaced/upgraded everything, at least once, since my first grow! I swear once I get new grow space dialed in all I gonna do is grow... 😎

[Potted]

I use a six inch 440 exhaust fan with a built in speed controller it helps to remove heat or at lower speed it keeps heat in!

[D.A.A.S.69]

Yeah mine's a 6inch with a knob you can turn down, an in my 63inch tent it don't get over 78degrees even when I got the 315cmh turned on super lumen an the exaust fan turned down, got great negative pressure. Yeah a little mores always better.

[PuravidaC]

Put 12 inch oscillating fan back in and bumped up humidity, running at 77 degrees with rh at 45. Loving it!!