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This article will explore five checks that you can do to determine exactly when you should replace your fish tank heater.

If you’ve been keeping fish for some time, you know how important it is to have a well-functioning, high-quality fish tank heater.

After all, your aquarium is home to your fish, and it should be as comfortable as possible.

Fish are cold-blooded, and their body temperature is sustained through their surrounding waters’ temperature.

Heat must always be provided to the fish at the ideal temperature, and a suitable, safe setup is also key.

You may have a fish tank heater in place and be unaware if it is even working properly.

This essential piece of equipment requires constant maintenance and checks to ensure your pets’ safety and health.

Are you sure that your fish aquarium is being heated properly? Or is it time for a replacement?

When Should You Replace A Fish Tank Heater

You’ll need to replace your heater when it stops working. Regularly check the temperature of your water, is it consistent or fluctuating? is it too cold or too hot? is your heater damaged? If you notice any of these issues you should replace your heater. 

Now, let’s take a look at several factors to help you determine if it’s time to replace the fish tank heater.

Top Rated Fish Tank Heaters

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When Should You Replace A Fish Tank Heater

1. Check The Condition Of Your Fish Tank Heater

You should check your heater every once in a while and see if there are any signs of damage on it.

You can check it by unplugging it, letting it cool then remove it from the fish tank.

Inspect it for wear and tear, cracks, and its overall condition. If there are mineral deposits that can be removed, then clean them.

However, if the heater looks clearly worn down, it is best to replace it.

Related: Can A Fish Tank Heater Catch On Fire

2. Check The Size & Rating Of Your Heater

Depending on your aquarium’s size, your fish tank heater should have enough power (watts) to heat the entire tank sufficiently.

Generally, 3-5 watts per gallon is recommended for most aquariums. So a 50W Heater would be perfect for a 10-gallon fish tank.

For 55 gallons or less, we recommend a 5 watts per gallon heater. For over 60 gallons, a 3 watts per gallon heater is more suitable.

Always ensure that your heater has enough power or wattage to heat the size of your aquarium.

If it is too low or too high, it is advised to replace it.

3. Look For Temperature Fluctuations

Most tropical freshwater fish need a temperature of about 78 degrees. A safe range is from 78° to 80° F for most species.

The temperature should be consistent and not fluctuate greatly or frequently. It should only fluctuate between 1 to 2 degrees within the range in 24 hours for a general idea.

If your aquarium temperature fluctuates more than 1 to 2 degrees, it means your heater is malfunctioning, and you need an immediate replacement.

4. Check Thermostat Control

Most heaters come with temperature settings that let you control and set the temperature.

To keep the tank at the desired temperature, the thermostat needs to work.

If the heater’s settings are not keeping the tank at the desired temperature, the thermostat is no longer accurate, and you need to find a new, more reliable heater.

One of my favorite heaters is the EHEIM Jager Aquarium Thermostat Heater. Eheim is one of the top brands in the industry so you can be sure this heater will last a long time.

5. Check Your Aquarium Thermometer

It would help if you were sure that your fish tank is being heated properly.

But for that, you need a properly functioning aquarium thermometer.

As a rule of thumb, if it has been a few years, it is always better to get a new thermometer.

For maximum accuracy, digital thermometers are recommended.

However, a stick-on LCD thermometer will do just fine and easily readable.

With a good quality thermometer, start regularly checking the temperature of the tank water. This will give you an idea of whether the heater is doing its job.

For maximum results, place your thermometer as far away from the heater as possible, this will give you the most accurate reading of the tank’s overall temperature.

Also, look for any damage or cracks on the thermometer.

Further Reading: How To Use An Aquarium Heater

Video: The Truth About Aquarium Heaters (and Why They Always Break…)

Final Thoughts

Heat failure can be dangerous for your fish, and it puts their lives at risk.

Always follow these instructions every few months when completing your regular maintenance checks and look for signs of damage.

It is important to monitor the temperature, thermostat, condition, and functioning of your heater regularly.

Lastly, please ensure the temperature in your aquarium is suited for your specific fish species.

We hope this guide helped you know more about fish tank heaters and when it is time for a replacement.

References