I threw a carboy with 5 gals of water that was abou 93 degrees into one of the cooling chambers. In the ice chamber, I put about 3 gallons of cool tap water into a bucket, added three frozen 2-liter bottles of water to that, and added seven more frozen 2-liter bottles of water into the ice chamber (not in the water). I cranked up the pump and fans and although it's only a couple of hours into it right now it LOOKS like it is going to work!!