Sobo Aquarium Heater (100W) helps to provide a healthy and safe abode to your pet fish. You can adjust the temperature as per the convenience of your fish from a range of 20-32Ã‚Â°Celsius. An inbuilt thermostat constantly monitors the temperature of the tank water. Any time the current temperature touches the level set by you the heater would automatically start heating the water to keep the temperature from dipping any further. It would keep the heater on till the time the temperature rises from the security level you have marked in the heater. The power lamp would also turn on along with the heating, pointing out the working of the heater. IMPORTANT:- Always place the heater near a filter as effective heating can only take place when there is a strong circulation of water to evenly spread the heated water all around the tank. It is important to consciously think about the wattage of the heater you purchase. Only after considering the size of the aquarium, and the difference between room temperature and the desired aquarium temperature, choose an appropriate wattage of heater for your fish.