Home made media for beneficial bacteria in my tank?

Thanks John, but it was my understanding that ammonia and whatever else the bacteria feed off of to create the cycle was found throughout the whole tank as well as the bacteria themselves, not just in the filter. A few places I've read up on say to not do gigantic gravel cleanings if ammonia or nitrites are high because it will get rid of the beneficial bacteria that live throughout the gravel. Also, I don't see how adding sponge differs much from any other bio ball or similar product that is supposed to just be an object with a lot of surface area for the bacteria to cultivate on other than the manufacturers make the products specifically for that purpose. Correct me if I'm mistaken or missed some part of the cycle that would negate my logic. Any outside references would be helpful :)