As part of my refugium design I added a liter of Cerapore (manufactured by Aqua Medic) to the section that receives the water from the main tank. These are little ceramic cylinders about an 1 1/2" long and 1" diameter. They look like sponges. Anyway, Aqua Medic claims that anaerobic bacteria may form in them when completely submerged in a tank.

Does anyone have any experience with these? Have I just added another nitrate factory to my tank?

A pic of my sump can be found in moonlighting