Hi all. I know it's product question but nobody answers in that forum! And it's filtering my Malawi tank so it's cichlid discussion! So the clear intake and outlet tubing on my canister is really gross looking. U can't see it as tank back is covered but its discolored and almost looks like mold spots inside it. Do I clean these or is it ok to let them look grimy since they're hidden? Any hints how I clean them if so?