I have a double sponge filter which I use as a pre-filter for a canister. They recommend replacing the foam every 3 months. The foam is fairly fine so over time they do clog up. The replacement sponges have been unavailable for some time. Mine are almost 2 years old. I rinse them out weekly but they really were past it now with a significant reduction in flow. So today I dropped them in a bucket of hot water (not boiling) and chucked in some H202 (hydrogen peroxide). Left to soak for half an hour and the sponges are now as good as new - and the water in the bucket is pitch black.
Be aware that this will kill all the bacteria in the sponge so not recommended as a routine cleaning method
Be aware that this will kill all the bacteria in the sponge so not recommended as a routine cleaning method