I have Eheim 2217s and 2213. I used to clean only once every couple of months. I am wondering how often do you clean your canister filters? I realize it depends on the stock level, so you can assume it is 100% stocked.
Ouch, monthly is a bit painful if you have multiple tanks with multiple canisters. I did think about going pure bio for canisters and chemical (I guess some extra bio here too) for HOB filters before because of this reason...depends on the tank.... mostly monthly