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How to fix the Fluval E Series Heater red light issue

Your Fluval E Series Advanced Electronic Aquarium Heater may display, or even flash, a red light. This indicate that there is a problem with the water temperature in your fish tank.

To see how you can potentially fix this problem, you can take a look at this article here at Aquarium Blueprints.

It should be mentioned that this guide will cover all models of the E Series, which should include the following:

  • Fluval E50 Advanced Electronic Aquarium Heater
  • Fluval E100 Advanced Electronic Aquarium Heater
  • Fluval E200 Advanced Electronic Aquarium Heater
  • Fluval E300 Advanced Electronic Aquarium Heater

Why the Fluval E Series Heater is showing a red light

If the LCD screen on your E Series is showing a red light, then it means that the current water temperature in your fish tank is at least 1 °C or 2 °F warmer than the temperature you set for the heater.

Why the Fluval E Series Heater is flashing a red light

If you see the LCD screen flashing red, then it indicates that the current water temperature is currently at least 3 °C or 5 °F above the set temperature of the heater.

How to fix the red light issue with the Fluval E Series

If you want to stop the LCD screen of your E50, E100, E200 or E300 from displaying or flashing a red light, then you can try taking the following steps:

1. The red light doesn’t necessary mean that something is wrong with the heater. Instead, it may indicate that the ambient room temperature is causing the tank water to be warmer than usual.

So, if you believe that the ambient room temperature is too hot, then you can try cooling it down. To do so, you can try airing out the room by opening a door or window.

You can also try removing the aquarium top if you have a closed. If you have a small fan, then you can also try putting it near your fish tank in order to cool it down as well.

If you live in a region that is constantly warmer that your desired tank water temperature, then you might want to consider getting a chiller so that you can keep your tank water cool when the ambient temperature gets too hot.

2. If your room temperature is cooler than the set temperature of your E Series, then there may be something wrong with the heater.

To start off with troubleshooting the your E50, E100, E200 or E300, you should see if the water line in your tank is above the minimum water line of the heater.

If the tank water is below that line, then you need to add more water in your tank in order to go above the minimum. Otherwise, the temperature sensor may be inaccurate at reading the water temperature.

3. If you took the heater out of the water while it is still plugged into the water, then it could also cause it to not work correctly.

In this case, we suggest that you unplug the heater from the power outlet and then leave it out of the tank water for a minimum 1 hour. Afterwards, you can submerge the E Series back in the aquarium (make sure that the minimum water line of the heater has been reached). Next, you need to wait for at least 20 minutes before plugging the device back into the power outlet.

To see whether or not you can install the Fluval E Series on its side, you can take a look at this post.