IMHO, canisters are the devil.
You have a small, limited space for all your media...and then it's a PITA to access that little bit of media to boot. Inevitably it doesn't get cleaned as often as I feel a filter should...and if by some miracle you do clean it that often, you end up wearing out or breaking some tiny expensive back-ordered part by constantly flexing/snapping/twisting/etc.
And, of course, with so little media in a canister it's only natural to worry about killing any of the beneficial bacteria, not only in the biomedia but also on the mechanical media as well. Like Esox and duanes said, a sump gives you so much room for biomedia that you can clean the mech stuff as often as you want, leaving the biomedia untouched and undisturbed and knowing that your bacterial population remains practically the same.
When I am home I remove and thoroughly rinse the initial layer of mechanical media (a relatively small sheet of foam) in my sumps literally every day. My well water is of course non-chlorinated, but I've done the same thing when dealing with chlorinated municipal water without issue. Removing as much solid organic waste matter as possible and doing it this often prevents much of it from ever undergoing bacterial decomposition into ammonia/nitrite/nitrate and keeps my water that much cleaner because of it. It takes mere minutes to do, and pays big dividends. And, when I am away from home for work for three weeks at a time, sometimes for many months, this initial foam layer can go that long without cleaning...although of course the nitrate production will be increased for that period.
I also use a lot of sponge/Matten filters in smaller tanks, and tend to use much larger sponges than are typically seen in many aquariums. This, of course, is much more difficult, sloppy and inconvenient to clean in the manner described above, so I content myself with simply vacuuming the outer surface of the sponge periodically, and then once in a great while removing the dang thing and giving it a thorough rinse/squeeze/repeat until the water comes off mostly clean. Even though done in tank or non-chlorinated water, this must remove a good percentage of bacteria, but I have never had any problems as the remaining population is sufficient and re-establishes the required number of bacteria very quickly. But no matter how you slice it, a sponge or Matten is the quintessential form of the type of "nitrate factory" described by duanes. It is, IMHO, their one failing.
Sorry for going on too long. TLDR version: clean biomedia as little as possible (I don't touch mine, sometimes for years!). Clean mechanical media as much as possible (every day for me). And for heaven's sake, don't replace anything! Of course the instructions tell you to; they want you to keep buying their overpriced stuff! Use a quality, durable foam like Poret for your mech media; a piece will last for many years and many hundreds or thousands of vigorous rinses and squeezes, will filter as well as or better than any disposable product, and will (despite being expensive initially) save you a fortune when amortized over its lifespan.
You have a small, limited space for all your media...and then it's a PITA to access that little bit of media to boot. Inevitably it doesn't get cleaned as often as I feel a filter should...and if by some miracle you do clean it that often, you end up wearing out or breaking some tiny expensive back-ordered part by constantly flexing/snapping/twisting/etc.
And, of course, with so little media in a canister it's only natural to worry about killing any of the beneficial bacteria, not only in the biomedia but also on the mechanical media as well. Like Esox and duanes said, a sump gives you so much room for biomedia that you can clean the mech stuff as often as you want, leaving the biomedia untouched and undisturbed and knowing that your bacterial population remains practically the same.
When I am home I remove and thoroughly rinse the initial layer of mechanical media (a relatively small sheet of foam) in my sumps literally every day. My well water is of course non-chlorinated, but I've done the same thing when dealing with chlorinated municipal water without issue. Removing as much solid organic waste matter as possible and doing it this often prevents much of it from ever undergoing bacterial decomposition into ammonia/nitrite/nitrate and keeps my water that much cleaner because of it. It takes mere minutes to do, and pays big dividends. And, when I am away from home for work for three weeks at a time, sometimes for many months, this initial foam layer can go that long without cleaning...although of course the nitrate production will be increased for that period.
I also use a lot of sponge/Matten filters in smaller tanks, and tend to use much larger sponges than are typically seen in many aquariums. This, of course, is much more difficult, sloppy and inconvenient to clean in the manner described above, so I content myself with simply vacuuming the outer surface of the sponge periodically, and then once in a great while removing the dang thing and giving it a thorough rinse/squeeze/repeat until the water comes off mostly clean. Even though done in tank or non-chlorinated water, this must remove a good percentage of bacteria, but I have never had any problems as the remaining population is sufficient and re-establishes the required number of bacteria very quickly. But no matter how you slice it, a sponge or Matten is the quintessential form of the type of "nitrate factory" described by duanes. It is, IMHO, their one failing.
Sorry for going on too long. TLDR version: clean biomedia as little as possible (I don't touch mine, sometimes for years!). Clean mechanical media as much as possible (every day for me). And for heaven's sake, don't replace anything! Of course the instructions tell you to; they want you to keep buying their overpriced stuff! Use a quality, durable foam like Poret for your mech media; a piece will last for many years and many hundreds or thousands of vigorous rinses and squeezes, will filter as well as or better than any disposable product, and will (despite being expensive initially) save you a fortune when amortized over its lifespan.
