Review on Eheim Jager Aquarium Thermostat Heater: Optimal Temperature Control for Your Aquatic Environment by Erica Williams

Update: After almost a year of use this heater was not working properly and burned my entire aquarium killing over 30 fish. I happened to walk past the tank and FELT the warmth of the glass. That's when I noticed all the dead fish. I put the thermometer in the tank and it read OVER 100 DEGREES before I pulled it out and jerked at the heater. I'm sure the temperature was over 100 degrees. I threw 3 trays of ice cubes into the tank and added 10 gallons of cold water to try to even out the temperature in the tank and save the few surviving fish from dying. My guess is that I should have returned the heater after the initial problems listed below. I am so disappointed because Eheim products are usually well made. If you decide to buy this heater, set it on a timer so it turns off from time to time and use the thermometer alarm system on your tank. Or just buy a more reliable heater. Original Rating: Severely overheats the tank. I set it to 73 to start, just to make sure I didn't overdo it when the heater was a bit warm and my thermometer in the tank read 88 degrees! This resulted in 5 of my fish dying from heat stress within a few days even after I removed the heater. I turned it off and reset it to 63 but my tank still got to 81 degrees. After turning it down to the lowest setting I'm finally sitting at the correct water temperature of 76-78 degrees. If you don't want dead fish, test it in an aquarium with no fish first.