I prefer to use undergravel so probably am not best placed to advise on other filters but I do have one bottle-type I use from time to time.
It contains activated carbon, and sponge only. I have tried cutting down sponges to 50% and putting ammo-lock chips in with reasonable success. But it works fine with the sponge and carbon only.
The sponge will trap a great deal of the solid or suspended matter and will be the main home of the good bacteria you want to engender. The carbon also retains bacteria on surface but helps keeps smells down too...someone else please add more on carbons properties...
The ammo-lock is to try and keep levels of ammonia and nitrites down but this does slow down cycling, I believe.
Other mods I have done are to cut down the blades on the impellor so that the current created is lessened...not reccommended unless you can obtain spare impellers or your an engineer like me and can calculate how much to hack off.
