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

I have been using Eheim for years as it is a trusted industry brand. Unfortunately, I can no longer use this heater brand. The temp I set right out of the box (78*F) brought my tank up to (82*F). I don't know how hot he would have gotten if I hadn't caught him doing it. Even with the heating setting (74*), (80*) was still registered in the tank. I currently have the heater set at 73* and the tank temp is reading 78.9* fairly stable all week. The discrepancy was annoying, but I could deal with it. Recalibrating didn't do anything. I recently got home and the heater was still set at 73*F and my tank was at 82.4*F. The heater kept heating and wouldn't turn off. Luckily I only have one clownfish in this tank that is hardy and tolerates such temperature fluctuations. I've had clownfish for almost 14 years now and I'm not going to lose him to a crappy heater malfunction. This Eheim is going in the bin and I will never buy from this brand again. I bought another heater on Amazon for my son's 10 gallon salt tank for $5 cheaper and it keeps showing 77*F and guess what? It was set to 77*F right out of the box. No problem with other brands. From now on they receive all my cases.