One challenge when operating an aquarium is to constantly maintain the environmental conditions in the complex underwater world. A thermometer is important to control the water temperature: the temperatures in the natural habitats of fish and other inhabitants of the aquarium tend to remain fairly stable. If the water in the aquarium is too warm or the temperature drops too low, this can quickly result in fatal consequences for the fauna and the plants in the tank. The aquarium thermometer is an essential accessory in aquaristics.

The aquarium thermometer remains in the tank and continuously monitors the water temperature. There are three thermometer types specifically designed for use in the aquarium:

• Liquid thermometer: The measuring liquid in a narrow glass tube expands according to the ambient temperature, and the level can be read on a scale. Liquid thermometers are often made of glass and are sensitive. Never select a thermometer with mercury as the measuring liquid for your aquarium!
• Thermometer strips: These are affixed to the outside of the aquarium and show the temperature with thermochemical colour change; the temperature values may be affected by ambient conditions and room temperature. They are used for temporary tanks, but you should always have a proper thermometer for your permanent tank.
• Digital thermometer: The water temperature is measured via a sensor that has contact with water. Among the digital models, there are precision thermometers that send a warning signal as soon as the water exceeds or falls below the ideal temperature range. These practical tools can show defects in the aquarium heater. A digital thermometer is battery operated.

Aquarium thermometers for precise water temperature measurements are available in our online shop from  AniOne and JBL.

Liquid thermometers are mounted directly in the tank. You can choose between floating thermometers or aquarium thermometers that are attached to the glass with a suction cup. Depending on the model, some aquarium digital thermometers are also installed directly in the tank. Alternatively, a thermometer can be mounted on the outside of the tank while the sensor protrudes into the water through an inconspicuous cable. The measurement should not be performed too close to the heating element. You get an average value at half the tank height.

A high-quality liquid thermometer displays very precise readings: any deviations from the actual water temperature are about 0.5 degrees Celsius. A digital thermometer can be used to measure the water temperature even more precisely: a sensor can record the water temperature to one decimal place.