How Do I Know If My Aquarium Heater Is Working? 4 Essential Steps You Can Take Right Away

Last Updated on May 5, 2022 by admins

How do I know if my aquarium heater is working? Stay with us and learn more about aquarium heaters and how to tell if it is broken.

The heater is unquestionably one of the most important pieces of aquarium equipment. Its role is to heat the water and maintain its temperature at the appropriate level, i.e. to keep it warm and cozy for the aquatic critters. It is a must-have for the fish to survive in the tank. Always keep in mind that there is one trick, a heater can kill your fish if it doesn’t work properly.

Therefore, it’s no wonder many people are wondering “how do I know if my aquarium heater is working”. Read below as we discuss some critical points related to this topic.

Reasons Why Your Aquarium Heater Is Not Working Properly

Before you find the answer to the question “how do I know if my aquarium heater is working”, we need to clarify why this problem occurs at all. There are many reasons why your heater may not be working, read more about each of them below.

  • Sometimes the device can be unplugged, with no power running through it.
  • If your aquarium light is on, but the heater and water don’t feel warm enough, consider changing the light itself. There was probably loose or broken contact inside the aquarium heater.
  • The heater isn’t the right size; it is too big or too small for the needs of your aquarium tank.
  • Your heater may have cracked or salt may have formed on it. It is not uncommon for glass to crack, metal to corrode, or colors to change, it is only important to be careful and replace the damaged parts if possible.
  • You forgot to turn off the aquarium water heater during the last water change and now your device has broken down because it was running dry.
  • You have not placed it near the circulation points and it can’t distribute the temperature evenly throughout the tank.

 Do fish tank heaters turn on and off?

How Do I Know If My Aquarium Heater Is Working? – A Short Guide

Read below to see what steps you can take if you suspect your device is defective.

Step No. 1 Check the Light

This is really the first and easiest step to take if you want to check if your aquarium heater is working properly. Note that in some cases the light will not work which means your heater may be faulty.

Step No. 2 Check the Water Temperature

It’s time for the second step. Here you can use a thermometer or even your own hands to check the water temperature inside your aquarium tank. In case you plan to use a thermometer, place it in your fish tank before starting the aquarium heater. Then, turn on the heater and watch for a change.

Keep in mind that sunlight can also affect the temperature rise, therefore place the tank in a neutral zone. In addition, you can check the temperature with your own hands. Wash your hands, put them in the tank and slowly move towards the heater. The water should be warmer as you approach it.

Step No. 3 Increase in Heat

The next answer to the question “how do I know if my aquarium heater is working” can be found in step 3. Simply check the temperature of your room and then the water in your aquarium.

Furthermore, set the heater at a higher temperature than the water and check if the light is on and if the water is heating up gradually. Its correctness is easiest to determine with a simple test with a lamp. If the heater works properly, it will automatically blur everything close to it and you will have a clear answer to your question.

Step No. 4 Bucket Testing

In addition to hands and a thermometer, you can test your heater in a bucket of water. Since the bucket is quite smaller than your aquarium tank, you will find out the answer to the question “how do I know if my aquarium heater is working” much faster.

Fill the bucket with water and measure its temperature. Then insert the heater, turn it on and wait for at least 2 hours for it to warm the water. Ultimately, you can use a thermometer to determine if the water has become warm or not.


 What does a green light mean on a fish heater?

The importance of an aquarium heater probably can’t be emphasized enough. This device keeps the water at an appropriate temperature to sustain life. Without that, the consequences would be incalculable. Unfortunately, this is one of the fatal situations that most hobbyists usually notice when it is already too late.

When the water temperature is too low it can stress your aquatic pets and lead to lower immunity and diseases. Therefore, it’s a good idea to do regular checkups.

That would be it, now you know the answer to the question “how do I know if my aquarium heater is working”.

If you have any questions, please let us know in the section below.

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How Long Does It Take For An Aquarium Heater To Work?

On average, it takes between 25-and 40 minutes for a heater to warm up the water in your aquarium tank. However, this is greatly influenced by several factors, the most common of which is the size of the tank itself. Once heated, it can start doing its job.

What To Do If My Aquarium Heater Is Not Working?

Simply buy a new one. Don’t play around and try to fix it yourself because you can cause various problems, and injure yourself or your pets.

Do Fish Tank Heaters Turn On And Off?

That's right, the aquarium heater has the ability to automatically turn on and off. It will turn off after the set water temperature is reached, and turn it on again once the water starts to cool down.

What Does A Green Light Mean On A Fish Heater?

Most heaters have indicator lights that let you know when the heater is on/off. If you notice that the green light on your heater is on, it means that your device is in standby mode. This is good because it means that the desired water temperature in the aquarium has been reached.