How do you rinse the filter? Do you remove the media or do you rinse it as well? Also sometimes food will get on the rim of frame of the aquarium. Do you use Dechlorinator during wc's?
I cleaned both the filter and rinsed the sponge inside in water I took out during water changes. There was quite a lot of slime in the filter, more than I ever find in other filters that I clean far less frequently. I assume its algae? Could this algal growth be due to a partial filter crash I had in this tank about two weeks ago? Because part of the bacteria died off, the algae were able to get a better foothold?