Cascade presents the 100W LED Aquarium Heater by Penn-Plax. This heater easily maintains healthy water temperature within a 1° accuracy and can be set anywhere between 68 ℉ and 89 ℉ by using the red control knob. Our Cascade Aquarium Heaters are factory set to 76 ℉ and are safe for either freshwater or saltwater fish tanks. The 100W model works great for 15 – 20 gallon tanks. Shop Penn-Plax for all Your Pet’s Needs: Penn-Plax is a manufacturer and distributor of top quality pet supplies who specialize in creating excellent pet products for animals both great and small.