Amazon.com: Hitop 50W/100W/300W Adjustable Aquarium Heater, Submersible Glass Water Heater for 5 – 70 Gallon Fish Tank (50W for 5-15 Gallon) : Pet Supplies
Amazon.com: HITOP 25W 50W 100W 200W 300W Adjustable Aquarium Heater, Submersible Fish Tank Heater Thermostat with Suction Cup (50W) : Pet Supplies
Tetra HT Submersible Heater 50 Watts, For Aquariums Up To 10 Gallons, UL Listed - Walmart.com
Amazon.com: Tetra HT Submersible Aquarium Heater With Electronic Thermostat, 50-Watt, 2-10 Gallon : Pet Supplies