Best Aquarium Heater 20 Gallon

HiTauing Aquarium Heater, 50W/100W/200W/300W/500W Submersible Fish Tank Heater with Over-Temperature Protection and Automatic Power-Off When Leaving Water for Saltwater and Freshwater

NICREW Aquarium Heater 100W, Temperature Adjustable Fish Tank Heater with Controller for 10-20 Gallon, Overheat Protection

HiTauing Aquarium Heater, 100W Fish Tank Heater with LED Digital Display & 5 Safety Protection, Submersible Aquarium Heater with 2 Suction Cup and 5.9Ft Cord for 10-20 Gallon Fish Tank.

Abhirsh Aquarium Heater 50 Watt - Reliable Fish Tank and Immersion Water Heater, Adjustable Temperature Submersible Thermostat Heater for 5-10 Gallon

Eheim Jager TruTemp Submersible Heater - 50 W

Fluval T100 Fully Electronic Aquarium Heater, 100W, up to 30 US Gal / 100 L

hygger Newly Quartz Fully Submersible Aquarium Heater, 100W/2002/300W/500W/800W Fish Tank Heater with LED Display Controller for 10-190 Gallons Marine and Freshwater (100W for 10~25 Gallon)

Aqueon Adjustable PRO Aquarium Heater

SainSmart XpertMatic Submersible Aquarium Heater, 100W Adjustable Fish Tank Heater Thermostat with Suction Cup, for Marine Saltwater and Freshwater, Up to 20 Gallon Fish Tanks

Hagen Fluval Marina Submersible Heater for Aquarium, 100W