I have bought this heater many times and for various sizes of tanks. My oldest Eheim heater is a 300 watt in a 75-gallon freshwater aquarium and has been running for 4-years. For this reason, I decided I needed to replace this heater before it goes bad and that is what prompted this review.The only issue I have is that the thermostat is sometimes off a few degrees even after following instructions and setting it properly. Because of this, I found it easier to monitor the temperature with a separate gauge and if the temperature exceeds what I want within the tank, then I twist the dial down a degree or two. Also keep in mind that the lights over your aquarium will heat the water a few degrees so it’s best to do this with the lights off.Some of the older reviews for these heaters mentioned overheating. If you’re also worried about this, you can buy thermostat controllers that come with a probe you place in the water and when the temp exceeds the temperature you set the controller will turn off the heater. Inkbird makes a very reliable and cost-effective version of this called “Inkbird Freshwater Saltwater Aquarium Heater with Probe Thermostat”.Overall, I have been very happy with the reliability of these heaters. When paired with a thermostat controller as mentioned before you should never need to worry about this heater overheating your tank.
