External Thermostat – Basic

The External Thermostat – Basic is a plug-and-play safety controller that sits between the mains outlet and any aquarium heater. A sensor probe placed in the tank continuously monitors water temperature, cutting power to the heater when the setpoint is reached and restoring it when the water cools.

This simple device transforms any dumb heater — including glass and titanium models — into a more safely controlled heating system. If the heater's internal thermostat sticks in the on position, the external unit cuts power, preventing a catastrophic cooking event.

The analog dial typically spans 20–34°C, and the large indicator LED confirms when power is being delivered to the heater. Essential equipment for fish rooms, breeding setups, and any installation where livestock is too valuable to risk on a single point of failure.