Richard pointed out a mistake I made in a previous post in this thread. Nitrobacter is thought to be involved in the nitrite step of the ntrogen cycle, not the nitrate step. Actually, Micrococcus, Pseudomonas, Denitrobacillas, and Bacillus are the bacteria thought to be responsible for dentrifcation.

In case anyone is interested in learning more about the nitrogen cycle, and filtration in general, here is a good link:

http://www.reef-aquarium.net/resourc...iltration.html