How do I clean an aquarium filter without killing bacteria?

Remove the filter media and rinse them in old aquarium water or dechlorinated water to remove any accumulated waste. Coarse sponge pads are the dirtiest and can be vigorously wrung to clean it as much as possible. Bio media houses beneficial bacteria and should be gently agitated (not scrubbed) in the water. Chemical filtration needs to be replaced entirely when used up (unless you’re using Purigen, which can be cleaned with diluted bleach). The frequency of filter maintenance depends on many things, like the size of the filter, amount of media, and amount of food being fed to the aquarium. As a rule of thumb, we recommend setting a calendar reminder to clean your filter every 1-3 months.

For more information on filter media, read the full article here.