Oase Heatup 200w have a built in thermostat and are fully submersible.
This Heater is recommended for the Bioplus Thermo 200, Filtosmart thermo 200 and the Biomaster thermo 350 but also can be used in aquariums.
The Heater can be adjusted between 18 and 32 degrees Celsius and has an led light indicator to show when the heater is working.
Led power indicator
For freshwater or Marine