oh yeah I understand that. I started taking care of an assisted living tank and it was so bad!
I also take care of a 55g gold fish tank with 2 HOBs and a new 2 week old canister, the HOB
filter pads ( which I cut myself) rarely have debris, they just turn black in spots...
my 29 g fancy goldfish tank has 2 HOBs ( 1 is a aqua clear I added a week ago)
my fluval canister on my 60g community tank: the filter pads are generally dark but mostly tinted a green color