How Does an Aquarium Temperature Controller Work?

Tropical fish require a specific, narrow range of water temperature to survive. For tropical aquarium enthusiasts, a temperature controller, which automatically maintains an aquarium's water temperature within a specified range, is a useful piece of equipment. While temperature controllers are not foolproof, a high-quality temperature controller can help an aquarium owner make the environment a healthy and stress-free subsistence for the sunbelt swimmers.

  1. Temperature in the Tropical Tank

    • A tropical fish aquarium must be maintained at between 72 and 84 degrees Fahrenheit to provide a suitable environment. While this temperature range seems to provide some leeway, some fish require an extremely narrow range from 75 to 77 degrees. Fish exposed to temperatures that are not ideal for their species, and fish that experience a rapid temperature fluctuation, will become physically stressed. Stressed fish will become ill and may possibly die.

    The Water Heater

    • A water heater maintains the temperature at the level required by the fish species residing in the tank. Most fish tank heaters have temperature controllers built in. These controllers usually take the form of a knob or another selection device located on the regulator portion of the heater. Many water heaters have a built-in thermometer, which allows the aquarium owner to determine the water temperature at a glance. The size of the tank determines the recommended heater wattage.

    The Temperature Controller

    • A temperature controller is nothing more than a thermostat. A thermostat may consist of mercury contained within a glass tube, like the thermometers your mama -- or maw-maw -- used. Regardless of what type of thermostat your unit uses, when the water's ambient temperature rises, heat causes the mercury to expand within the submersed tube. As the mercury expands down the tube, the farther end of the tube drops, closing the contacts and shutting the thermostat valve. This position is referred to as the ̶0;closed position.̶1; As the temperature cools, the mercury back up the tube. This process closes the opposite set of contacts while opening the other, causing the heating circuit to turn on again. This position is referred to as the ̶0;open̶1; position.

    Temperature Controller Problems and Troubleshooting

    • Not all thermostats are manufactured with equal care. At times, an inexpensive aquarium heater will get stuck open or closed. If the thermostat sticks in the open position, the water will begin to lose heat. Quite often, this could cause the temperature to become inadequate to maintain the ideal environment for tropical fish, leading the fish to become stressed.

      If the heater is stuck in the closed position, on the other hand, the water will become too hot. In such a case, the fish will die from one of two possible causes: First, they may succumb due to the temperature. Second, they may not have sufficient oxygen in the water to enable them to live. Keeping a second thermometer in the water provides a fail-safe: Check it every day at feeding time to compare temperatures and take swift corrective measures if necessary. A daily peek at the temp might be enough to save your fish's lives in the event of a temperature controller failure.