I setup a 2' x 3' x 5' grow box with a 250w MH light in a closet. The room is hot and the temperature in the grow box stays between 79-85 degrees / 50-60% humidity (with lights off) Is this suitable for vegetative growth? I still need to build the hydro system but am worried about the temperature being a problem and am trying to remedy that before I continue. I am considering creating an intake with ducting to the room's window to suck cooler air from outside or possibly setting up a small AC unit. Are these temperatures a really big problem? How can I most efficiently remedy this problem? Thanks in advance.
how much hotter will it get with the light on???? I would recommend some type of ac unit or fresh air intake.......85 is max temp....you get any higher and your plants will not want to grow as much in the heat....like you and i when it get over 30c, id rather sit in my ac'd house and do nothing too....make sense....... key is air flow...cooler the better...
with a few fans and a good intake and exhaust system you should be good. Is your light air cooled? if not you could try to make a cooltube for it and that would help keep the temp down.
Run a 24-48 hour test with the lights on in you Grow chamber and see how much exactly temps rise and humidity changes! Let me know because I've had a similar question...