Well, the other media would either be carbon inserts or the BioMax (ceramic rings in a bag). The carbon isn't really necessary unless you are removing meds or something, and the BioMax shouldn't ever have to be replaced, as it is just basically more surface area for bacteria to colonize. The package tells you to replace the Biomax every 3 months or so, but I think they just do that to make you spend more money, because why would anyone throw away perfectly good bacteria, you know?
I don't use any carbon in mine, I just use 2 foam blocks stacked on top of each other, with the BioMax on top of that. Works great!
As for the flow rate of the 110, I can't really comment as I have never used one larger than the 70, I just know that they are rated to 500 gph
and that seems like overkill for the 29. I know the flow rate is adjustable, but I bet it is pretty strong even when it is turned down.