Review on 🐠 EHEIM Jager Aquarium Thermostat Heater 100W: Reliable and Efficient Heating for Your Aquarium by Jennifer Moore

The heater keeps the temperature in the tank good, but that's not the temperature I'm aiming for. This device is either not powerful enough for the Eheim rating or my device is defective. The temperature is very different - runs much colder than set. The thermostat can be "calibrated" by moving the red needle to match your individual tank's thermometer, but my heater is over 10 degrees from the lower calibration limit. 93F and it still won't get my 28 gallon tank above 78F. I bought a 100w unit that Eheim rates for 26-40 gallon tanks so that should do the trick. I've tried several configurations with placement around the tank, trying to install it vertically and horizontally in the tank to no avail.