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How to fix Fluval E Series Heater low flow issues

If you have been using the Fluval E50, E100, E200 or E300 Advanced Electronic Aquarium Heater in your fish tank, you may notice that the letters “LF” flashing on its LCD screen.

To see how you can potentially get rid of this error message, you can check out this this troubleshooting article from Aquarium Blueprints.

What does the LF error message indicate?

If you see LF flashing on the LCD screen of your E Series heater, then it means that there is not enough flow going through the heater. While the heater will still be heating the tank water, it won’t be doing so efficiently due to the lack of water circulation in your aquarium.

Furthermore, there may by certain spots in your fish tank that will be colder due to a low flow.

How to get rid of the LF error

In order to fix the low flow issues of the E50, E100, E200 and E300 Advanced Electronic Aquarium Heaters, you can try doing the following:

1. To start off, make sure that you position your heater directly.

Fluval recommends that you place the E Series directly next to the output nozzle of your filter or water pump.

Keep in mind that the sensor is located near the top of the heating unit. So, you can try putting the top third of the heater to the same level as the output nozzle of your filter or pump if possible.

If you need to move the heater, we recommend that you unplug it from the power outlet first. You can then move the device as long as you keep it in contact with the tank water at the minimum water level.

If you do need to remove the heater from the tank water at some point, then you need to wait at least 30 minutes after you unplug it from the power outlet to do so. You then need to wait 20 minutes after putting your heater back into the tank before plugging it back into the power outlet. If you do not wait, then you will risk potentially demanding the heating or sensing mechanism of your E Series.

2. If you are able to increase the flow rate of your filter or water pump, then you can try doing so.

3. You may also try adding an air stone of bubbler near the heater as these will also generate water movement as well.

4. If your E50, E100, E200 or E300 gets too dirty, then it may be blocking the water flow. Organic wastes buildup or mineral deposits may also cause the flow rate sensor to be inaccurate.

Therefore, make sure that your heater is as clean as possible.

Once your heater detects an increase in water circulation, it should automatically re-calibrate on its own. If it detects that there is enough water flow to efficiently heat up the water in your fish tank, then the LF error message should go away from the LCD screen.