How To Clean A Filter?

Sponges need to be squeezed in old tank water that you take out during a water change. They only need squeezing gently to get the muck off them, they'll never look like new again. In an emergency you can use dechlorinated tap water. Although some reckon plain untreated tap water is OK for well established filter media, I would rather err on the side of caution and add dechlorinator to tap water.

Ceramic noodles/ball etc need rinsing in old tank water as for sponges. Depending what their container is like, you might be able to shake the container to clean them or they may need to be emptied out. Again, don't scrub them to make them all shiny new.

As for the filter casing, I scrub that under the tap using a toothbrush (a cheap one bought just for tank things) to get at the awkward places. Yes this will kill the bacteria on the surface of the casing but they area tiny proportion of the total number of bacteria.


You'll read a lot of people saying don't clean all the media at one go, though I've never had problems doing that. If you don't want to risk it, clean one bit of media, then another bit next water change.



Have I missed anything?

Don't forget you may need to clean the impeller sometimes if flow seems reduced.
For several weeks I had a problem with one of my filters, no matter how well I cleaned the sponge and the impeller, I couldn't get the flow up to what it should have been. After trying several times, I finally adopted the scientific approach, turned everything upside down and banged hard on a table top. Rattle, clatter, out came at least 20 small snails which had been blocking up the passages. Back in tank, whoosh of water and all back to normal. The fish immediately started moving about the tank much more, I think the weak flow had meant that the temperature wasn't being equalised, warmer at the top than the bottom, one of the other things that a filter does.

In my case, I clean the filters weekly during water changes as I find the flow reduces if any less frequently than that. I find plant debris (especially java moss) clogs up the filters easily.