Fluval recommends that you clean the impeller of the FX6 canister filter every 3 months and replace it every year.
You can check out this tutorial from Aquarium Blueprints to see how you can properly clean and replace the motor unit.
1. To start off, make sure you disconnect the FX6 canister filter from the power outlet.
2. With the power turned off, you then need to drain water out of the canister. In order to do so, you can follow the steps detailed in this guide.
3. After draining the water, make sure that the “IN” and “OUT” valves have been completely closed off. The red dials for these valves should be horizontal.
4. The utility valve at the bottom of the FX6 should also be completely closed off as well as its red dial should be in the vertical position.
5. Disconnect the “IN” and “OUT” valves from the top of the filter, remove the top cover and then take out all the filter media baskets.
6. Use a cross headed screwdriver to unscrew the four screws holding the protruding motor unit.
7. Pull the motor unit away from the FX6 canister and then turn it over to reveal the impeller.
8. Hold the second layer of the black part in the motor unit and then pull the impeller out of the impeller shaft.
You should also make sure that you don’t accidentally remove the seal ring. If you did, make sure your place it back to its original location, which should be right above the ridges.
9. Inspect the impeller to see if there is any potential damage. If you don’t see any damage, then you can skip ahead to Step #14.
10. If you do see some damage, then it is best that you replace the impeller with a new one.
If you are looking for a replacement part, then you can check out the Fluval FX6 Aquarium Canister Filter Maintenance Kit on Amazon with this link. (#CommissionsEarned)
11. Use the metal tool included in the aforementioned maintenance kit to remove the O-RING and bushing that are inside the impeller shaft of the FX6 motor unit.
12. You can then use the bushing tool from the kit to insert the new O-RING and bushing into the shaft.
13. Afterwards, you can insert the new impeller unit from the maintenance kit.
14. Next, you can use a cleaning brush or cloth to wipe off any debris that you see on the impeller.
15. You should also clean impeller shaft in the motor unit.
16. Finally, make sure that you clean the inner area of the FX6 canister where it connects to the motor unit.
17. Once you are done with all the cleaning, make sure you re-insert the impeller back into the impeller shaft if you haven’t done so already.
The black arrow on the impeller should be pointing towards to red arrow. You also shouldn’t be able to twist the black impeller unit around if it is firmly in place.
18. Screw back in the motor unit back into place on the FX6 canister filter.
19. After reinstalling the motor, you can add back in the media baskets that you previously removed.
20. Next, you need to add 2 gallons or 8 liters into the canister.
21. Put the canister top back on and then re-connect the “IN” and “OUT” valves.
22. Make sure that the “IN” and “OUT” valves are set to the fully vertical position.
23. You can then plug the Fluval FX6 back into the power outlet.
24. The canister filter should automatically start pumping water and dispersing excess air.
25. After a few minutes, your FX6 should operate normally again.
For a visual walk through of how you can clean and replace the impeller of the Fluval FX6, you can take a look at the maintenance video made by the official Fluval channel below: