Cooling grow tent

i have a 3x3x6 grow tent. my newly transplanted seedlings are about 2 inches tall. i have fans inside and out of the tent to get air moving. the temp stays about 86 degrees. is this too hot? if so any suggestions on a cheap way to drop the temp? my light is a 600watt metal halide. its all i have so i have to make it work. humidity is about 40%. thanks


If the room your tent is in is colder than your tent you can run an extraction fan. Suck the air out at the top, and open a fresh air vent at the bottom of your tent.


I have trying to figure out the same thing I will try that tonight

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I would say 86 is a little too high… if the seedlings are still small you could create a dome out of 2 litre clear pop bottles. That way you can mist the bottles (not the plants) and create a more humid environment. How far are the lights from your plants? Are you able to keep your tent open during lights on to bring temp down a little?

Not the greatest pic but this is a popular pop bottle method during seedling phase


thanks so much for the reply and the pic. i just measured and the plants are about 4inches tall and roughly 4 inches wide. the light is about 4foot away. its non adjustable. would the bottles not make it hotter? I’m new at this. my plants are a little further along than the ones you sent in the picture. where do you get a fan like that? or will any small fan work? just place it over the opening on top of the tent? thanks so much.

When I was running MH/HPS I used cool tubes with ducting and cheap inline hvac fans exhausting all the heat from my tent



I have never used anything outside of led but 4 feet away from the plants may cause the plant to stretch too fast and have a very weak main stem… the heat is definitely an issue that can be solved by what @Packee is showing but the fact that it isn’t adjustable will cause problems… 40% humidity is quite low for seedlings/early veg aswell. I don’t see a solution to these problems without spending a bit of money on cooling/ducting, and a setup that can be adjusted in heights.

Best of luck!