Tetra 26446 HT Submersible Aquarium Heater With Electronic Thermostat, 100-Watt, Multicolor, 10-30 Gallon;

All Tetra HT heaters have red/green indicator lights to let you know when the heater is heating(red) or on standby(green). The low voltage thermostat maintains water at 78°F without any adjustment required. Be sure purchase the correct heater for your tank size. Buying a heater too small for your tank can cause under heating. It is critical to ensure your tank is equipped with a hood or glass canopy to contain the heat inside the aquarium. All Tetra HT Heaters will shut off if an electrical short is detected for your safety.