Review on Submersible Fish Tank Heater - 500W Digital Aquarium Heater with Readout for 60-100-150 Gallon Saltwater or Freshwater, External Thermostat Titanium Safe Controller, Includes 2 Artificial Plants as a Gift by Ashley Branch

A quick physics lesson, if this device doesn't draw even 500 watts from my outlet then it can't radiate 500 watts of heat into my water. On average, it draws around 370 watts from the socket, so it probably only emits around 360 watts of heat. I thought the price was too good to be true. Edit: So it's been holding up like a champ in my 120 gallon fresh water tank for the past two weeks. I have the temp on my heater set at 80 and my water thermometer reads 79 every time I check it. I have an aquarium at work and the room it is kept in is actually quite cold so I am impressed with the ability of this heater to handle that temperature. The only reason I'm not giving this five stars is the inaccuracy of the performance. But other than that it seems like a good heater for the price. The next test is now pending, the time has come.