Nano Stat Aquarium heaters come complete with an inbuilt thermostat that automatically turns off the heating elements when the aquarium water reaches 25J. This makes it ideal for maintaining a stable water temperature all year round perfect for growing most tropical plants and fish species. The heater can be positioned on the back glass or integrated into the back filter of Interpet Nano Aquariums. Features: Reliable keeps temperature at a tropical 25J. Compact design for flexible positioning. Safe and durable with run dry protection sensor. Available in 10w (up to 12 litres/2.6 gallons) or 25w (up to 25 litres/5.4 gallons)