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Fish Tank Thermostats

What Is a Thermostat, and Do I Need One for My Aquarium?

(The First Tank Guide)

What is a Thermostat?

A thermostat is a device use to automatically switch another piece of equipment on or off based on temperature changes. Thermostats are usually used to turn heating appliances on when the temperature drops below a set minimum or to turn cooling devices on when the temperature rises above a set maximum. Thermostats will also turn a device back off when the desired temperature is again reached.

Your home heating and air conditioning will have a thermostat to turn the heat on when it gets too cold and to turn it off again when your home has warmed up, or to turn the air conditioner on when it gets too warm and turn it off again once the house has cooled. Your refrigerator and oven also have thermostats to turn them on or off based on the temperature settings you select.

Why Have a Thermostat in a Fish Tank?

In an aquarium, a thermostat is necessary to properly and safely run an aquarium heater or chiller. By correctly setting your thermostat, you can properly maintain your aquarium temperature.

Where Do I Get a Thermostat for My Fish Tank?

Most aquarium heaters and some aquarium chillers come with built-in thermostats, so you have a control right on the heater or chiller to set the thermostat to maintain the desired temperature. On handing heaters, this is usually on the top of the heater in the form of a flat knob. For submersible heaters, this is usually a small knob or nipple sticking out of the end of the heater next to the cord. This knob or dial can be turned one way to increase the temperature setting for your fish tank, and the other to lower it.

Some aquarium heaters and chillers come with a remote thermostat which is separate from the heater element or chiller and is placed in a different location in the aquarium. Heaters and chillers with remote thermostats like this tend to do a better job of maintaining an even and consistent aquarium temperature. However, it is usually not necessary to keep a very exact temperature in your aquarium, as water temperatures in nature tend to fluctuate over time. It is, though, important to be familiar with the species and varieties of fish you are keeping to know how much temperature fluctuation they are likely to tolerate (and what temperature range they want to be kept in).

There are also aquarium heaters and aquarium chillers that do not come with their own thermostat. These heaters and chillers will require you to purchase a separate thermostat unit to control the heater or chiller. These are particularly handy when you have a tank in a situation where it is likely to be too cool during winter months, but too warm during the hot summer. With an independent thermostat like this, you can often control both a heater and a chiller with the same thermostat and maintain your aquarium temperature in the correct temperature tange for your fish that way; using the chiller or the heater as appropriate, but not having the two compete with each other.

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