I got one of these heaters for my first tank, a 10 gallon. It worked well, but didn't keep the water at 78 like it said it would, although it stayed at 76 which is fine for my fish. I would recommend using this heater for anyone with fish that are fine with water temps 72-80*. When I bought my second tank, I got another one. It kept the water at about the same as the other one. it is a fairly good product. I have 2 ten gallons, a 2.5, a 55, and a 3 gallon. The two tens and the little tanks have this heater and all of the tanks with this heater stay at 76*.