Precise Temperature Regulation - 100W fish tank heaters for tropical features a 0.5C accurate thermostat to maintain a stable tank temperature, automatically shutting off at the set point. This ensures the comfort of your aquatic pets and saves energy. Overheat Protection - 100W aquarium heater includes overheating and dry run protection. It alerts with "H1" at temperatures above 34/93F and stops heating. "E1" indicates dry run, halting operation when water is too low. Space-Saving & Efficient - 100W small aquarium heater is ideal for small tanks with its compact design. For precise temperature control, adhere to instructions: set up proper water circulation and clean the tank regularly. Operate within the specified voltage and avoid touching the water when the heater is on to ensure safety and efficiency. Convenient Temperature Management - 100W small fish tank heater features an external controller, eliminating the need for wet hands or manual dial adjustments. Easily set your ideal tank temperature. Remember, the controller is not waterproof; keep it dry to avoid damage and ensure safety. Wide Range of Use - 100W heater for fish tank fits both freshwater and saltwater tanks, suitable for a variety of aquatic life including tropical fish, neon tetras, guppies, angelfish, goldfish, betta, and sea turtles. Features strong suction cups for easy, secure installationensure full submersion for optimal performance.