We may earn a commission if you buy something through the affiliate text links or affiliate image links on Aquarium Blueprints.

What to do if the Fluval E Series Heater is not heating

If your Fluval E50, E100, E200 or E300 Advanced Electronic Aquarium Heater does not appear to be properly heating your fish tank water, then you can check out this troubleshooting article from Aquarium Blueprints to see how you can potentially fix your problem.

1. To start off, you should make sure that the top of your tank water is below the minimum water level label of your heater.

If you fail to meet the minimum level, then your heater may not be able to detect the correct water temperature and, therefore, may not properly heat up your tank.

2. You should also check the LCD screen of the heater.

If the screen is green, then it indicates that your tank water is within the set temperature range of your E Series.

If the screen is blue, or flashing blue, then it means that the current tank water temperature is below the set temperature range. To see how you can deal with these blue light issues, you can take a look at this guide.

3. If some areas of the tank appear to be cooler than other areas, then you may have a water circulation problem as the heat may not be able to reach these isolated spaces.

To fix this problem, you can try increasing the flow rate oy your filter output or water pump. You can also add an air stone or bubbler to the colder areas to improvement the water circulation.

4. If the LCD screen of the E50, E100, E200 or E300 is showing a LF error code, then it means that the flow rate is currently too low for the heater to properly warm your entire aquarium.

To see how can fix this low water flow problem, you can check out this article.

5. Placing your Fluval E Series horizontally or diagonally should make the heater more efficient when it comes to heating up your tank water.

6. We also recommend placing the heater as close to the bottom as possible without it touching the substrate or other objects. Since heat will rise from the heater, this will make sure that the bottom of your tank is properly heated.

7. You can also try letting the ceramic heater core cool down before using it to heat up your tank water again. In order to do so, you can try taking the following steps:

  • Unplug the E50, E100, E200 or E300 from the power outlet.
  • Wait for a minimum of 20 minutes so that the ceramic heater core will adjust itself to the current temperature of your fish tank.
  • Plug the heater back into the power outlet.

8. Organic wastes and/or mineral deposits may be hindering the heating ability of your Fluval E Series Advanced Electronic Aquarium Heater. Therefore, you may want to give the device a thorough cleaning.

To see how you can clean the E50, E100, E200 and E300, you can follow the steps laid out in this article.

9. There is a possibility that your E Series is defective. In this case, you will need to get a new heater for your fish tank.