Ok I'm growing in a closet, inside a cabinet which I am currently leaving the doors open on because of the heat. I'm using a 600 watt hps light and I'm having heat issues. Even with a fan blowing directly on the bulb I couldn't close the doors because the temps would be way too hot. I have nowhere to exhaust heat out of the closet either. I'm considering some type of small airconditoner, but I have no idea where to find one. Can I put a 400watt bulb in a 600 watt light? It's a hydrofarm light with a remote ballast, so I'm assuming the ballast would be fine since the bulb would be smaller. It's not a big deal leaving the doors open but it's not very stealthy. Also, I don't want to buy a 250watt light because I already bought this, hell of a deal I bought it used for 75 bucks.
i can only say that you could have a few fans blowing air onplants/out of room and a 1 on high blowing fresh air in hope this helps!
DON'T PUT A 400 WATT GLOBE IN A 600 WATT BALLAST!. I did and my globe exploded and fucked my ballast. If you want a 400, put an add on ebay to trade your 600 for a 400. I reckon it'd take 2 seconds for someone to snap up that offer. Most ppl want more light not less so there is heaps od people of will trade you. If I had some offer to give me a 1kw for my 600 I could get my hands on it fast enough!