Questions about Environment and AC Infinity Equipment

I am getting ready to do my first grow and have a few questions.

Temperature: My grow tent is in my basement. It is winter here in Virginia. With the lights on, I can get to 75F. When the lights go off at night, the internal temperature of the tent goes down to 61F. Will this be acceptable to the plants or should I put in a heater of sorts?

Air Flow: To get to 75F, with the current basement temp of about 61-+, the fan is not running at all (exhaust not circulation). Should the fan run at a low level constantly? If I put it on level 1 as the default, I can’t keep the temp above 72F. Can I leave the fan on auto and have it only kick on periodically or should there be a constant exhaust?

Humidity: Since it is cooler and dry this time of year, my RH is at 34%, with two wet sponges in the tent. Will this be acceptable? I will get more sponges, and likely a humidifier.

VPD: What is a good value for VPD leaf temperature offset? I have no clue, but I bet those of you that use AC Infinity controllers have figured out a good plug in value.

Thanks for your help. I am not a big user, but my kid and friends spend way to much money on weed and it is legal to grow here, so I am trying to save them some bucks. I am retired, an automation nerd and have time to figure this out.


Welcome to the community, I hope this answers some questions, and others will chime in as they find this.

Lights on if you can get closer to 80° it would be better.

They may grow a little slow at this temperature. I try for 70 and above for lights out.

This would best. Placing some additional fans in the space to move air around will be more helpful. The only reason to run the exhaust fan is to exchange the air out, and it’s unnecessary to have it run on high, especially in veg period. Flowering higher speeds are necessary to keep air moving, and to keep negative air pressure in the tent to keep smells down.

34% is acceptable for flowering. I shoot for 50% or less, and lower the better. Veg it should be higher at about 50% or higher, but temperature is more important than RH.


You may need a heater to get the temp up. Like @Covertgrower said, couple more fans would help.


Welcome aboard!! You’ll find that VA is well represented here. Is your bsmt floor concrete? Some growers have stated previously that putting a buffer between the floor and your tent will help insulate the plants from the chill. Is a space heater an option for the evenings down there? Good luck @BlueRidgeDog


Hi @BlueRidgeDog . Im in Va. as well near Richmond.
I know its already been said, however, a few fans attached to your tent poles will help with your circulation. A humidifier will also help with your RH during veg. I sometimes keep a small bowl of water in my tents and air moving around will help with the RH while the water in the bowl evaporates. Also damp towels will do the same thing.
However, the biggest problem I’ve had so far with humidity being so low is drying too fast after harvest.
Good luck on your first grow!:blush:


Okay, since the consensus is that it needs to be warmer and wetter, I have ordered a small 400w space heater for inside the tent, along with a 7L humidifier. Each will be controlled via a smart switch using the home automation system I use. I can’t tie the automation system to the data from the AC Infinity controller, so I will put a standalone temperature and humidity sensor in the tent. Will see how the numbers shake out then. I may put the tent up on a layer of insulation, but I bet the heater keeps it easily in the right range since it is close with the heat from the LED light.


Agreed generally, but perhaps what you can do is just feel the bottom of your pot after you’re all set up and running. If it’s not cold, you’re good - save the time and money. If it is, perhaps you want to go there.

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If it is the bottom of the pot that is of concern (root issues?) then I could easily put the pots on slabs of 1" insulation board. Basement is cold! But in the summer it is the perfect temp and humid.


My tent (2x4) is in a shed that I’ve insulated except the floor and has a nice portable heat/ac unit. The shed is on blocks and it’s been cold (for here) recently. I was getting a 10+ degree spread from the top to the bottom of the tent. I actually put the tent up about 1-2” on small risers to level it (different story :slight_smile: ) and the air flow under there just from the ambient temp inside leveled it back out inside too. Now it’s a little warmer under the lights of course but not too far off.

Having said all that, I guess the deeper roots go outside, the colder it gets, so maybe it doesn’t really matter. That’s gradual though, not like being in a nice warm blanket and then putting your bare feet down on tile :rofl:

Someone here knows the science for best practices re: the effects of temperature on the roots.


This will work great! Just want to keep the warmth from getting sucked out into the slab.


@BlueRidgeDog, Just a thought if you have the room, and a smaller tent.
I have a small tent, that was put on a platform. These allowed a drain to be put through the bottom of the tent, and the run off goes into a drain pan placed under the platform. Makes run off management easy.
I later converted it to the drip hydroponic system that is in the picture.

Welcome to the forum! We also live in the Blue Ridge area of VA.


The temps are almost exactly where I run except mine go up to 80 with rhe lights on.

I added a stab into my basement ductwork to add a touch of supplemental heat.

Blue Ridge Mountains of Virginia too. :slight_smile:


Welcome aboard. We look forward in seeing your beautiful flowers.