What to do When the Aquarium Heater Breaks?

Aquarium heaters are a crucial part of any aquarium setup. They control the temperature of your water and keep it at a level that is comfortable for your fish.

So what happens when a heater stops doing what it is meant to do? Perhaps, the heaters keep the temperature way above or below a fish tank’s temperature requirement. What do you do then?

What to do when the aquarium heater breaks? Obviously, you should replace it as soon as possible. A good fishkeeper always has a backup in case anything fails. In most cases, this is the difference between the life and death of fish. With a backup heater, you can replace the broken one as soon as you notice it.

If you can’t do it as fast as needed, you should try controlling the temperature of the aquarium room. Ideally, keep the temperature close to the fish’s optimal temperature until you get the heater’s replacement.

Why do Aquarium Heaters Fail?

The most common causes of aquarium heater failure are improper setup, faulty wiring, low water flow, or incorrect installation. When installing the unit make sure it has enough space to dissipate heat and that no objects will obstruct its airflow. If you have a fish tank in your room make sure not to put the heater near anything that might trigger an electrical fire such as curtains, clothes dryers, etc…

To avoid such problems with your fish or other aquatic life you should regularly check the temperature levels in the tanks and make sure that there is enough space for air to circulate so that hot spots can’t form on any object inside.

How do I Know if My Aquarium Heater is Broken?

If your heater is broken, you would likely notice a change in the temperature of the aquarium. For example, it might be either too hot or too cold.

Moreover, the fish’s metabolism slows down and they can no longer keep themselves warm. Fishkeepers notice that fish in their aquariums are less playful or active whenever something goes wrong. Such behavioral changes are great indicators of trouble in your tank.

The best way to determine if your heater is broken is by observing your water’s temperature. Measure the temperature of your tank’s water if you suspect that the heater is broken. The results will give you a clear picture of the heater’s condition.

How Long Can Fish Tank Go Without a Heater?

The answer is not very long. Aquariums need heaters to keep the water at a comfortable temperature for the fish. Without a heater, your fish will die from hypothermia in hours. The optimal temperature for some fish is about 65 degrees Fahrenheit (18 degrees Celsius). Some fish like those found in tropical waters, are more used to warmer temperatures and can live with higher temperatures around 76 degrees Fahrenheit (24 degrees Celsius).

When the Aquarium Heater Breaks: Steps to Ensure Safety and Maintain Temperature

  1. Ensure Your Safety First:

Before addressing the broken heater, prioritize your safety. Make sure to unplug the heater from the electrical outlet to prevent any potential electrical hazards. If the heater is submerged in water, avoid touching it with wet hands or attempting to remove it from the aquarium while it is still plugged in.

  1. Assess the Damage:

Carefully examine the heater to determine the extent of the damage. If the glass casing is cracked, shattered, or leaking, it is crucial to remove it from the aquarium immediately. Broken glass in the water can harm your fish and other aquatic creatures, and the leaking of any electrical components can pose additional risks.

  1. Remove the Broken Heater:

Using a pair of aquarium-safe gloves or tongs, carefully remove the broken heater from the aquarium. Be cautious not to cut yourself on any sharp edges or come into contact with any exposed electrical parts. Place the broken heater in a safe container or wrap it in a thick towel to prevent any further damage and to dispose of it properly.

  1. Monitor the Temperature:

Without a functioning heater, it is essential to monitor the temperature of the aquarium closely. Temperature fluctuations can stress your fish and make them susceptible to diseases. Consider using an alternative method to maintain a stable temperature, such as:

  • Room Temperature: If the ambient room temperature is within the acceptable range for your aquarium inhabitants, it may be sufficient to maintain a stable environment temporarily. However, be aware of any changes in room temperature due to weather conditions or heating/cooling systems.
  • Spare Heater: If you have a spare heater available, carefully install it according to the manufacturer’s instructions. Ensure that the new heater is appropriate for the size of your aquarium and capable of maintaining the desired temperature range.
  • Partial Water Changes: Performing partial water changes with pre-conditioned water at the desired temperature can help regulate the aquarium’s temperature to some extent. Gradually add the conditioned water to avoid sudden temperature shifts.
  1. Seek a Replacement Heater:

Once the immediate situation is under control, it’s important to invest in a new, reliable aquarium heater. Consider the following factors when selecting a replacement:

  • Quality and Reliability: Choose a heater from a reputable brand known for manufacturing high-quality, reliable products. Read reviews and seek recommendations from experienced aquarists.
  • Wattage and Size: Select a heater with an appropriate wattage for your aquarium size. The general guideline is to have approximately 3-5 watts per gallon of water, but this may vary based on the specific needs of your tank.
  • Safety Features: Look for heaters with built-in safety features such as automatic shut-off mechanisms to prevent overheating and temperature controllers for precise temperature regulation.
  • Heater Placement: Consider the size and design of your aquarium when selecting a new heater. Ensure it can be securely and discreetly placed in the desired location within the tank.
  1. Regular Maintenance and Monitoring:

To prevent future heater failures, practice regular maintenance and monitoring of your aquarium equipment. Clean the heater periodically, following the manufacturer’s instructions, and check for any signs of wear or damage. Regularly monitor the temperature of your aquarium using a reliable thermometer to ensure a stable and comfortable environment for your aquatic pets.


We hope that the tips and tricks we have provided have been helpful. The next time your aquarium heater breaks, you’ll be ready with a game plan!