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 Most aquarium experts recommend that you determine your heater’s power in terms of watts per gallon (WPG). Typically, you will need around 2.5 to 5 watts per gallon in your tank. So, for example, a 10-gallon aquarium would need a 25- to 50-watt heater. Still, this is only a rough estimate—you will also need to consider the room temperature to make an accurate calculation. If your room temperature is low, you will need a larger heater to raise the water temperature in your tank—a cold room may require more than 5 watts for each gallon of water. Fully Considerations for Undesired Situations Dry Run Protection The fish heater prevents dry operation with an error code (E1) if not fully submerged. Submerge it completely to remove the error and resume function. Overheat Protection The fish tank heater stops and displays H1 if water exceeds 95℉/35℃, resuming when it drops below 93℉/34℃. Memory Function The turtle tank heater automatically resumes the last temperature setting after a power cut, no reprogramming needed. Easy to Set Simply press the "SET" button, and the temperature will increase by 1℉. When it reaches 93℉, pressing it again will reset it to 59℉. Press and hold the set button for 5 seconds to switch from ℉ to ℃. Indicator and Dual Temp. Display The fish aquarium heater features indicator lights: a red light signifies active heating, and a blue light indicates temperature maintenance. Additionally, the digital display shows both the current water temperature and the target water temperature. Suction Cups To make placement convenient, the fish heater comes with suction cups. These suction cups allow for easy and secure attachment in your fish tank.