Eheim 125 Watt Thermocontrol Aquarium Heater

The EHEIM 125 W thermocontrol offers adjustable heating for freshwater and marine aquariums. The temperature dial covers 18–34°C, and a control light makes it easy to see when the thermostat is calling for heat.

A laboratory-glass jacket surrounds the heating element and spreads heat across the submerged body. The unit is watertight and incorporates EHEIM's dry-run shutoff, while the suction-cup holder keeps it positioned in the aquarium.

Check that the heater's length fits your intended mounting area before selecting this wattage. Heating requirements depend on the difference between room and aquarium temperature, alongside tank volume and heat loss. After installation, use a separate thermometer to confirm the water reaches the intended temperature; recalibrate the dial if the manufacturer's procedure indicates that adjustment is needed.