Setting up a new canister filter (Fluval) in a 33 gallon Cichlid tank. I'm going using the new Model 205.
In the past, with older Fluval models that had only three (3) stages I used the following in order:
Foam
Carbon
Bio-Max
This new model has a place to put five (5) different stages. Too many options!
Well that is the great thing about these new filters with multiple chambers, you can use what ever you would like. If you need to up your pH you could add some crushed coral, aragonite, dolmite etc. It is okay if you want to use the same media in more than one chamber also. I don't think I would use sponge in more than one, but definitely whatever type of media you do use, it will increase the area that good bacteria can grow, which is a good thing!!
Other items to consider are bio-balls, glass or ceramic beads, even just gravel will work.