Aquarium Canister Filter Help!!!?

I purchased a canister filter off ebay and in every tray it has a white filter wool pad. Well the pads are dirty now and I want to use regular filter wool cause its WAY cheaper. Each Tray has a filter pad and a media. One has carbon then the next has ceramic rings and the last has a blue filter pad on top of a white one then some Seachem Matrix. Is all this even neccessary? Can I use 1 for carbon, 1 for bio media and 1 for filter wool? The filter is working great but its time to clean it.