I have somethign similer to what you have. I got a 6 foot tall wood cabnit from home depot. I put the 400W hps at the top with a reflector. No cool tube nothing. I have 2 fans moving hot air out. One is to the left of the light and is a 6in fan. It pulls alot of air. The other is on the cieling and is just one of those little crappy fans. Anyway i cool the unit with A Ac wall unit (99$ walmart) i put it in the side in the middle. It works for me ive gotten some good dank out of it.