Review on 🐠 FREESEA Adjustable Thermostat Aquarium Fish Tank Heater: 50W, 100W, 300W with 2 Suction Cups & Thermometer - Ideal for Betta Tank, Saltwater Tank, Aquariums, Coral Tanks by Rob Vizitei

My first nano aquarium was a different model from this company and it worked fine. The temperature fluctuated within a few degrees, which was stressful for my fish. But it was good. For my second nano aquarium I tried a brand name heater from a local chain store. I stopped heating completely after three days. I then ordered another "famous brand" from Revain and it overheated even though it was the right size. In the end I decided that a few degrees difference is acceptable for this brand. It took several days to set the temperature. I had to set it lower than I wanted to stay fairly consistent in the 78.5-80°F range. But my tank has already completed its first cycle and the temperature remains fairly constant. I'm sure it won't stress my fish too much and thank goodness it won't cook it.