It's been years since I even looked at my heater, so not 100% what wattage or brand it is. But If I had to guess, I'd say its a Marineland 300W (heating my 125g by itself). I never really monitored my temperature until recently (planning on getting cichla in a month or so, and wanted to make sure water would stay warm enough). Tank temperature stays about 83-84 degrees fahrenheit. It runs alot though, and probably is why my utility bill kills me everytime I open it....but then, Tallahassee has the highest utility rates in the state so its hard to say.