Catalina Aquarium Electronic Controller & Titanium Aquarium Heater is designed with the most advanced electronics for user safety and accurate control of water temperature. NEVER expose the heater to air while on. If the heater is run out of the water the sensor will not work properly and the heater will crack if not turned off immediately. Run the heater in a place that will never run out of water. Make sure the controller is in a safe dry place and the titanium heating element is fully submerged.