sintered glass is a media that has extreme surface area for bacteria to colonise (last time I looked it up it was 10-15000 square feet per liter compared to 5-7000 ft per liter)
peat is only if you want to play with your pH, activated carbon is a waste of time unless yo have other problems which should be sorted by good fish keeping instead of chemicals.
just remember that the manual is made by a company that wants to make as much money as possible.
my canister filters contain (in order of inlet to outlet) coarse sponge, ceramic noodles, medium sponge, sintered glass (or more ceramic if budget does not stretch) fine sponge, filter wool.
only additive I use is TLC live bacteria and carbon if im using wundertonic. (or major tannin problem) tried a few and imo most chemical filtration is just a crutch for lack of BASIC fish keeping skills.
just remember they were keeping rather nice tanks over 100 years ago without all of this crap