In the AC filters that I run (40,70 and 110s) I use filter floss as a layer.
Sponge(s) on bottom
A floss layer then
Ceramic rings on top
I don't use carbon.
Carbon is useful to remove medication from the tank after treatment is over.
As I understand it, carbon looses it's effectiveness after about a month anyway.
I have added a second sponge to most of my ACs. If the floss you use is like cotton
balls, putting it between sponges would be a way to contain it.
The floss I use is in a roll. I cut it to fit (one or two thickness) and put it under the ceramic
When I clean the filter (rinse the sponge and rings in a bucket of tank water) I toss the floss...
(hey, that rhymes) and put in fresh.
I used to have Whisper filters. I made my own cartridges. Tear off the floss pouch, discard the carbon, then reuse the old plastic frames.
Cut the filter floss large enough to wrap around the frame and hand sew a pouch, like the replacements you buy.
Just use a simple stitch with white cotton thread.
I sometimes would put 3-4 table spoons of carbon in that filter before stitching it together.
Filters that have layers do a much better job in my opinion. But then, everyone has their own opinion and experience. :thumb:
Whether it's a canister or hob, if you can layer the media, you can customize it to your aquarium needs.
With AC's I'm able to keep the biofiltration housed in the sponge and ceramic rings and toss the larger debris caught in the floss.