Biological filtration by coarse sponge pad

[Sandip]

I have thought of using two eheim 2217 for my 150 gallon Discus tank. Since i do not have much problem in changing water everyday, i need the filter media to be more biological than mechanical.
What is the best biological media to be used? I have seen the Eheim 2217 contains a number of blue colored coarse sponge pad and one white fine filter pad. Are they the best biological media. Or should i use Ceramic Rings and Bio-balls instead?
May someone help me with the arrangement of the media inside the filter?
My aim is to get maximum possible biological filtration from the 2217. Help me with advice in this regard.

[plecocicho]

The best biological material are ceramic rings. They are manufactered at great heat, so they are really porousous with high number of microcanals, which can harbour bacteria, so they have a huge surface for filtration. However, you have to exchange them after a while, because those microcanals can get stuffed with fine detrit particle and cant harbour bacteria anymore. Regarding the brand, i can think of eheim and sera siporax.

[CraigG]

Why not the ehiem media rocks not sure what they are called but I had then in my old ehiem 2217