You can't just "throw in" HID lights. They are of course the best way to go, but require much more ventilation.

The answer is cool tube, and a 250 CFM fan pushing air through it. Air from outside your grow area, close to the floor. Pushing to outside your grow area close to the ceiling, but preferably to the outdoors. Cool tubes are great, because if done properly you can let your plants actually touch the glass. As you probably already know, this is good.

Heat problems are very easy to resolve. More, or at least more efficient, ventilation.
Opie Yutts Reviewed by Opie Yutts on . I need help now!!!! Well I spent the whole night awake watching over my plant. My 400watt hps showed up so I threw it in and wow did the temps ever sky rocket. My cab is usually about 73 or so in the dark and with the cfls it was usualy around 78. With the hps now they jumped to 90!!!! I know this is ok but I'd really like to drop it to a more manageable level. What's the best way to do this? My cab is 4x4x2 I have 2 fans inside moving air around and a squirrel cage fan off of an old hockey table. Would Rating: 5