Eheim Jager Thermocontrol Heater 25W 23cm (20-25L)


25 in stock

With the EHEIM JÄGER precision heater your fish receive exactly the right temperature – in any aquarium.

Obvious ideas often are the best ones. For example, the aquarium heater as a rod. The heating rod is simply hung in the water and heats it. It is true that the principle is still the same as decades ago. But a lot has changed in the meantime. And today the EHEIM adjustable heater is an ultra-modern electronic thermal device with the best available technology. A jacket made from special laboratory glass increases the heating surface, serves as a heat shield and ensures optimum even heat emission. And no matter if you want to heat a 20 or a 1000 litre aquarium – you have 7 sizes to choose from.

Benefits of the EHEIM JÄGER thermostatic heaters

    • Precise temperature adjustment from 18 up to 34 °C
    • Simple and safe recalibration (±2 °C)
    • Temperature control accuracy ± 0,5 °C
    • Heat kept at a constant level
    • Heating function is indicated by a control lamp
    • Completely submersible (watertight)
    • With automatic dry run shut-off (Thermo Safety Control)
    • A glass jacket increases the heating surface and ensures optimum even heat emission
    • Handy cable length ca. 170 cm
    • Including double suction cup holder
    • 9 sizes for aquariums from 20 up to 1000 litres
    • Suitable for fresh and salt water

    Installation Instructions:

    • Check device for damage.
    • Remove transit protection.
    • Fix suction cups to double suction cup holder and clip onto heater (not near the heating spiral).
    • Mount thermostatic heater with double suction cup holder vertically in the aquarium, fixing it in a place where water flow is brisk (filter outlets/vents).
    • Set temperature.
    • Plug into electrical outlet.

    Setting temperature

    • Turn the temperature selector ring to the desired temperature.
    • Monitor the aquarium water temperature using an accurate thermometer for at least 24 hours and make any necessary adjustments to compensate for calibration errors.
    • You should periodically monitor your aquarium water temperature with an accurate thermometer (Red light = heater in operation).

    Note: The temperature selector ring should only be used as a guide. Always use an accurate thermometer for water temperature measurement.


    If, after a day or two in operation the setting scale does not correspond to the water temperature, refer to the following procedure to recalibrate the heater:

    • Switch off the heater and unplug it from the electrical outlet.
    • Measure the water temperature with an accurate thermometer.
    • Turn indicator arrow (red) point to the measured temperature.
    • Set the desired tank temperature with the temperature selector ring (blue).