Well, when I purchased my MH lights, the lfs recommended that I also get a chiller. I wasn't sure at first, because I knew that many people just used fans w/ their MH's. In So Cal it gets hot. I've had the chiller for about 4 wks and I have to say it's works great. Where I live, during the day the house gets above 90[sup]o[/sup]. The chiller is a much better way to keep the tank cool vs using the AC to cool the house. I have the Arctic Chiller 1/3 hp. It's probably a bit more than what I need, but it sure does cool the tank down quickly. Very low noise. I highly recommend the arctic if you're in the market for a good quality chiller.