Best Aquarium Heater 20 Gallon

HITOP HP-608 Submersible Aquarium Heater 25W 50W With Thermometer and Extra Sucker Cup (50W)

PYPABL 25W 50W 100W 300W Aquarium Heater, Submersible Glass Heater for 5L-300Litres Fish and Turtle Tank (50W for 15-55L)

hygger Aquarium Heater, 100W Fish Tank Heater with Intelligent LCD Digital Display Thermostat Controller, for 100-200L Freshwater Saltwater Tank

AQQA Submersible Aquarium Heater,15W 25W 50W 75W Digital Fish Tank Heater with Intelligent LED Temperature Display and External Temperature Controller,for 30-60L Fish and Turtle Tank (50W)

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

hygger Submersible Digital Aquarium Heater 100W, Betta Fish Tank Turtle Tank Heater with Intelligent LED Temperature, Thermometer and External Adjustable Temperature Controller for 25-90 Liter

AQUAEL ULTRA HEATER ABSOLUTELY UNBREAKABLE - 25W 50W 75W 100W 150W Temp range 20-33°C Tropical and Marine Aquarium fish tank (ULTRA HEATER 50W (15-50 L Aquarium))

Eheim Thermopreset Heater 100W preset to 25c (for aquariums 100-150L)