Midnight

I have a 46g with ~600w of lighting on it, so it can get hot. To cool it I have a large 12v computer case fan blowing over the surface, and decent ventilation, and good surface agitation from a large power filter. I also run my light cycle starting at 6pm and into the night (since that's when I'm there). My temps peak at around 81. It also helps to run the AC of course :]

Hiya, It depends on the type of ballast you have. Check here: http://www.wamas.org/forums/index.php?showtopic=2902

Hiya, The fan in my old Coralife PC light was an 120vAC fan. It should say on the fan itself somewhere, generally on the sticker on one side (it may be facing away from you where you can't see it). Or you can follow the wires, if it's wired right to a plug, then it's AC, if it has a transformer then it's probably DC. I buy my DC fans from Newegg.com, and I haven't had to buy an AC one but here's a link to a place that sells them, but shop around. If you don't feel comfortable wiring in a replacement AC fan, get a friend who does to help, it's a simple job usually :] http://www.action-electronics.com/fans.htm#Ac