I have a Fluvel G6 on my Discus tank. I have a regularly scheduled cleaning program because I cannot have by canister filter turn into a breeding ground for bacteria (not the good kind). I have a sponge prefilter on the outtake that I clean a few times a week. The mechanical gets cleaned at least once a week. The chemical gets changes every four months. I clean/or change out ( small amounts) of biological media every four months. I have done this for the past three years without any problems to my nitrogen cycle. My discus would certainly let me know if i had a spike.