So I’m not sure how controversial this is, but I’ve had my canister filter over a year. I cleaned it once about 8 months ago using tank water, rinsing out and squeezing the sponges which were very black. Since then; I have never touched the filter, and I don’t see a reason to. The flow is just as powerful as ever; I have successfully bred discus, and the water is crystal clear. Am I in the wrong here?