If your Fluval FX4 or FX6 is not turning on, running or working correctly, then you can take a look at this troubleshooting guide at Aquarium Blueprints to see you can do to fix these issues.
1. The first fix you can try is to reposition your canister filter.
Fluval recommends that the FX4 and FX6 should be between 20 cm to 150 cm below the top of the water surface of your fish tank. Moreover, the hosing connecting to the “IN” and “OUT” valves of the canisters should be as straight as possible.
2. You should also make sure that you properly set up your FX4 or FX6 for priming.
The “IN” and “OUT” valves should be fully open as the red dials should be in vertical positions.
Before you start priming, place the output nozzle above the water surface to avoid water and air from falling right back into the canister.
Last but not least, you need to add some tank water before starting the priming process. For the FX4, you will need 1.6 gallons of 6 liters. For the FX6, you will need 4 gallons or 8 liters.
3. You can also try plugging the canister into another power outlet as the current one you are using may have some issues.
When using another outlet, make sure you wait at least 3 minutes. This is because it should take around 1 minute for the FX4 or FX6 to pump water into the canister. It will then stop for 2 minutes to evacuate air. After 3 minutes, it should be pumping water in and out normally.
4. Your FX4 or FX6 may not start up or work if it is clogged up.
To clean your canister, you first need to unplug it from the power outlet and drain the water from inside the canister.
You then need to remove the hosing and the top of the canister.
Afterwards, rinse the filter media with tank water you plan on removing from your aquarium. While you can also use tap water, you need to add an aquarium water conditioner into the tap water first so that you don’t harm the beneficial bacteria living on the filter media.
If the sponges and foams still look very dirty or clamped down after rinsing, then you will need to replace them.
To clean the hosing and intake tubing, blast water through it via a faucet or garden hose.
5. A dirty or broken impeller may also be the reason why your filter is not running properly.
The impeller, which is located inside the motor unit, needs to be cleaned on a regular basis. Fluval also recommends that you replace it once every year.
6. If none of the aforementioned solutions work with your issues, then we recommend contacting Fluval directly for additional support.
