Do Aquarium Heaters Make Noise?

Most aquariums have various electrical components, such as filters and heaters, that contribute to the tank’s effectiveness in maintaining and keeping your fish healthy. You must set up the aquarium heater if you want your fish to enjoy a relatively constant temperature.

The aquarium heater can have various types and components, but they all have a thermostat, which serves as a regulator for the heater. The thermostat is a little chip that senses the temperature difference between the tank water and the environment.

The heater gives a clicking noise, which is normal when it turns on and off in response to a change in temperature and when it has to emit more heat during the winter. Heaters can make a knocking noise as well but this means there is something wrong with it.

Although the heater can make noise based on other factors, the prominent noise is the clicking noise caused by the thermostat, which is due to the structural design of the aquarium heater.

aquarium heaters

Why Do Aquarium Heaters Make Noise That Isn’t Normal?

The heater has a significant benefit of maintaining the water temperature, which keeps the fish stress free, thus aiding their immunity against disease. Despite its advantage, most aquarium heaters have a structural defect of making noise due to the following factors:

  • The position of the aquarium heater: Most heaters work differently when placed vertically and when they are placed horizontally. The heat exchange between the heating element and the bi-metal strip is more direct than when the heater is placed horizontally. Therefore, some heaters can be noisier while sitting horizontally than when placed vertically.
  • Burning out of the heating element: Some aquarium heaters usually overheat and burn out due to the high heat released by the heating element. You can check the heating element for burn-out when you hear any noise.
  • A structural defect in the heater’s design: Some heaters have their controls placed immediately above the heating element. Due to this defect, you may hear a clicking noise when the element contacts snap close to turn on the heater. Suppose you hear a repeated clicking noise, it means that the contact is closing and opening intermittently, and this can hasten the heat cycle before the desired temperature is reached.
  • The closeness between the lower suction cup and the heating element: The lower suction cup of most heaters is very close to its heating element such that the heater makes repetitive noise when the water trapped between the suction cup and the heater glass expands.

How Do I Know If My Aquarium Heater Is Working?

Aquarium heaters are often cheap and easily accessible, such that you may even consider buying a new heater if you discover that the current one is old and defective.

However, before you replace the heater, you need to know if the current one is working perfectly or not by doing the following checks:

  • Check the heater light: This is the first and easiest step to know if your heater is working or not. You have a functioning heater if the light is on when plugged in. You may not see the light if your heater is made from metal or the lighting bulb is faulty. If you can not confirm the functional status of your heater using its light, then you need to use other methods.
  • Check the aquarium water temperature: You can use a thermometer to confirm if the heater is working by noting the change in the thermometer readings when the heater is turned on. You need to place the thermometer inside the tank before turning on the aquarium heater to achieve the best result. You can also use your hand to check if the heater is working in the tank.
  • Check using a bucket of water: This method will give you more assurance because it requires less time and water quantity to know if the heater is working or not. You should place the heater in a bucket of water. You can use a thermometer and your hand to feel the increase in temperature when the heater is turned on.

Suppose you have done the above checks, and you are sure that the heater is not working, then your heater may be either defective, broken, or not heat-proof to withstand varying temperatures.

Should My Aquarium Heater Be On All The Time?

Yes. Your aquarium heater should always be on because your pet fish need a relatively constant temperature to live a stress-free life. Most freshwater pet fish are usually cold-blooded, and they maintain their body temperature by relying on the surrounding water temperature. Therefore, leaving the aquarium heater on is the best way to keep the fish within the set temperature. It would be best to note that leaving the heater on at all times will not break or spoil the heater since the thermostat will automatically turn on and off the heater based on the desired temperature.

Can My Aquarium Heater Explode?

Your aquarium heater can explode, but explosions rarely occur. Valve leakage is a major reason why your heater can explode. Your aquarium heater can also explode if there is too much pressure inside your tank or if there is a blockage due to sediment deposition.

You should be aware that leaving your heater on at all times will not cause your heater to explode.

Should I Turn Off My Aquarium Heater At Night?

No. It’s best to leave the aquarium heater on all the time and let the thermostat do its job. Many people often think fish need lower temperatures at night because temperature decline usually occurs at night; suppose the fish live in the ocean. However, this is not true because many different cycles of heat mechanisms occur at night in the sea to keep the water warm.


Your aquarium heater is a crucial part of your tank; you need to maintain it if you want to keep your fish healthy and free from secondary infections. If your aquarium heater makes noise, the noise may be due to various factors, which should not affect your heater activity. But if the noise is occasional, you may need to get a new heater, change its sitting position, or move the suction cup further away from the heating element.

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