100 Watt Aquarium HeaterMaintaining a consistent and constant temperature in your aquarium creates an environment where your livestock can thrive. Too much temperature fluctuation can be very un-healthful for your aquarium eco-system. When water temperature drops below recommendation, heaters will heat and maintain the warm water needed in fresh and salt water eco-systems. This fully submersible heater is suitable for aquariums up to 50 gallons and has an easily adjustable and visible temperature setting. This model HT-100 100 Watt waterproof fully submersible aquarium heater is perfect for aquariums up to 30 gallons. The temperature is adjustable from 65* F and 93*F using the easy to adjust thermostat. Built with high impact safety glass and waterproof insulation. The design is compact and only stretches 9.8 inches long.