The Fish Keeping & Aquarium Guide.

What to Do If Your Aquarium Heater Stops Working: A Quick Guide

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Aquarium heaters are essential for maintaining a stable water temperature and ensuring the well-being of aquatic pets.

However, like any electrical appliance, they can malfunction or stop working.

When this happens, it’s essential to act quickly to prevent the water temperature from dropping too low or rising too high, which can be fatal for fish and other aquatic creatures.

If the heater in an aquarium stops working, the first step is to check if it’s still under warranty.

If it is, contact the manufacturer or retailer to see if it can be repaired or replaced free of charge. If the warranty has expired or the manufacturer cannot help, the next step is to troubleshoot the problem.

This may involve checking the power source, the thermostat, the heating element, or other heater components. Sometimes, the problem may be as simple as a loose connection or a blown fuse, which can be easily fixed.


Identifying the Problem

Recognizing Signs of a Malfunctioning Heater


When an aquarium heater stops working, it can be difficult to identify the problem. However, a few signs to look out for can indicate a malfunctioning heater. These signs include:

  • The water temperature in the aquarium is significantly cooler than the set temperature.
  • The heater is not turning on or off as it should.
  • The heater is making unusual noises.
  • The water in the aquarium is cloudy or discolored.

Checking the Heater’s Functionality


To determine if the heater is the problem, it is essential to check its functionality. This can be done by following these steps:

  1. Unplug the heater and remove it from the aquarium.
  2. Check the heater for any visible damage or cracks.
  3. Plug the heater into an electrical outlet and observe if it heats up.
  4. Use a thermometer to check the water temperature in a bucket or container after submerging the heater. The temperature should match the set temperature of the heater.

If the heater is not working properly, it may need to be replaced.


Immediate Actions


When the heater in an aquarium stops working, a few immediate actions should be taken to maintain the aquarium temperature and remove the faulty heater.


Maintaining Aquarium Temperature


The first step is to maintain the aquarium temperature. If the temperature drops too low, the fish and other aquatic life in the tank can be harmed. Here are some ways to maintain the temperature:

  • Add a backup heater to the aquarium
  • Increase the room temperature where the aquarium is located
  • Cover the aquarium with a blanket or towel to keep the heat in

Removing the Faulty Heater


The second step is to remove the faulty heater. Here are some steps to take:

  1. Unplug the heater from the outlet and let it cool down for at least 15 minutes.
  2. Remove the heater from the aquarium and place it on a towel or other surface that can handle the heat.
  3. Check the heater for any visible damage or defects.
  4. Dispose of the heater properly, following local regulations for electronic waste.

Always handle the faulty heater carefully, as it can be hot and potentially dangerous.


Long Term Solutions

Choosing a New Aquarium Heater


If the current aquarium heater has stopped working, it may be necessary to purchase a new one. When selecting a new heater, it is essential to consider the size of the aquarium and the type of fish that will be living in it.

A heater that is too small may not be able to maintain a consistent temperature, while one that is too large may overheat the tank. Choosing a heater rated for at least 5 watts per gallon of water in the aquarium is recommended.


Proper Installation of the Heater


Once a new heater has been selected, it is essential to install it properly to ensure it functions correctly and safely. Before installation, the aquarium should be emptied of water and cleaned thoroughly.

The heater should be placed where it will be completely submerged in the water but not where it will be obstructed by decorations or other items in the tank.

The heater should also be positioned near the water flow to ensure even heat distribution throughout the tank. Once the heater is in place, the aquarium can be refilled with water and the temperature adjusted to the desired level.

It is essential to monitor the temperature regularly to ensure it remains consistent and adjust the heater as needed.


It is important to note that aquarium heaters are not designed to last forever. Replacing the heater every 1-2 years is recommended to ensure it continues functioning correctly and safely.


Preventive Measures


Some preventive measures can be taken to prevent the heater in an aquarium from stopping working. Two critical preventive measures are:


Regular Heater Maintenance


Regular maintenance of the heater is vital to ensure it continues working correctly. Cleaning the heater regularly is essential to prevent the build-up of algae, which can cause the heater to malfunction. It is also necessary to check the heater for any damage or cracks, as this can affect its performance.


Monitoring Aquarium Temperature Regularly


Monitoring the aquarium’s temperature regularly ensures the heater works properly. A sudden drop or temperature increase can indicate that the heater is not functioning correctly.

It is recommended to use a thermometer to monitor the aquarium’s temperature and ensure it is within the appropriate range for the fish and plants in the tank.

These preventive measures can significantly reduce the risk of the aquarium heater malfunctioning.

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