Passive cooling means?
The room isn't hot in itself. When I turn the lamp off, the temps settle to normal house temps of about 22C in 10 minutes.

What I dont get is when I blew a crappy little fan over them with the door open the last grow, the thermometer registered around 27c. With a great freaking hi-tech fan and two massive holes in my wall, but no little fan blowing over them, I'm getting around 31C. WITH A SMALLER LAMP!!!

What about chopping off the sides of the reflector?
faithlessxxx Reviewed by faithlessxxx on . AAAARRGGHH!!! I DONT UNDERSTAND! I've just completed one grow in a 1.2m * 1.8m closet, its 3m high too. I had to keep the door open, and with just a dinky little fan blowing on them from the doorway, they managed to stay at about 27C all the way, under a 400w HPS. For this grow, I decided to do things a little better. I smacked out a 12 cm round exhaust hole at about eye level and a 10cm intake at roughly floor level. I inserted the 12cm flex ducting, pulled it all straight and inserted it into my brand new fan which I've Rating: 5