User-Friendly Operation Simple Setup Simply press the "SET" button, and the temperature will increase by 1℉. When it reaches 93℉, pressing it again will reset it to 64℉. Indicator Lights The small aquarium heater is equipped with indicator lights. A red light indicates that it is heating, while a green light indicates that it is maintaining the set temperature. Suction Cups For easy placement, the turtle heater comes with suction cups. These suction cups can be securely and conveniently attached to the aquarium. Comprehensive Measures for Unforeseen Circumstances Dry Run Protection Prevents the fish heater from running dry, displays error code (E1) if not fully submerged. Submerge to clear error and resume function. Overheat Protection Stops heating if water temp exceeds 97℉/36℃, displays error code (H1). The aquarium heater will resume heating once the water temp drops to below 93℉/34℃. Memory Function The fish tank heater automatically resumes last temperature setting after power outage, no need to reprogram. How to choose the right heater for your aquarium? There are 3 elements to consider to determine the right heater for your aquarium size: Room TemperatureAquarium Water VolumeDesired Temperature Experts recommend 2.5 to 5 watts per gallon (WPG). For example, a 10-gallon tank needs a 25 to 50-watt heater. Adjust based on room temperature, colder rooms may require more than 5 WPG.