GH-100W Glass Heater Maintain constant and stable temperatures for your aquatic creatures to thrive with AquaTopp’s GH-100W aquarium heater. This analog glass heater offers simple and easy installation with the use of the included suction cups and can handle aquariums up to 25 gallons. With the highly visible temperature setting, the GH-100W is easy to set and adjust to the desired temperature with the use of the Temperature Adjustment Knob. This powerful heater also has double insulation and is made from high quality insulated glass.