you should not have to replace sponges very often as long as you wring them out of all debis regularly(depends amount of fish, food etc. youll get a feel for it) For example i take apart and clean my fluval canisters on my 75g every 1-2 months about, always washing all parts in old tank water in a bucket from a water change(sameday). You might not have to do it that often but i prefer to!
What ive learned that most people do on this forum is:
-in hob and canister filters only use mechanical filtration(supplied ssponge) & biological filtration (your choice of bio media)
-put your carbon packs aside and save them for other uses (extraction of meds)
-use a secondary form of filtration to aid your filter and act as a back up (most popular sponge filter on air pump, its great for polishing and also hold bio mater)
-most importantly very frequent high volume water changes (i do about 50-75% a week)
it works great for me. Unless my filter sponge was deteriorating I've never replaced it. You don't have to replace or clean bio media. Just take 25 mins and wring everything out, swoosh the bio baskets in some tank water. I like to clean my impeller and housing with a little brush, and scrape the intake and outputs sometimes.
hope that was helpfull, MDB
p.s. what ever the filter may be, the ritual seems to be the same (in my experience).
