Sorry if I'm being to general, last thing i want to do is misquote any information. I had to reaaaly dig to find out if this was right for me, and in the end I basically just dove in. The best resource I found was from about.com
http://saltaquarium.about.com/cs/nitratecontrol/a/aa092702.htm
If i may paraphrase from the site:
"..as the water slowly works it's way down the spiral, the O-2 is consumed by AEROBIC bacterias, the same ones that are in your filter and make all the life possible. Somewhere around 3/4th's of the way down however, the O-2 levels diminish within the spiral, having been consumed by the aerobic bacterias higher up the coil.
[SIZE=-1]Now what? Well, now the ANAEROBIC bacterias begin to flourish, the very ones that feed on nitrate, not O-2! As the water continues its travels it encounters the main interior chamber of the cylinder. All those BioBalls are just waiting to provide area for more anaerobic bacteria to consume all the nitrate that wasn't converted inside the bottom 1/4 of coil. This is the "bank" that will allow the coil denitrator to continuously process more and more nitrate as it is produced within the display tank..[/SIZE]"
As we know Ammonia > Nitrite > Nitrate. What we are attempting to do here is cultivate a bacteria that turn the Nitrate into a gas that can escape into the atmosphere, rather than having to be handled exclusively by WC. In an O2 free environment their competition can't survive.
http://saltaquarium.about.com/cs/nitratecontrol/a/aa092702.htm
If i may paraphrase from the site:
"..as the water slowly works it's way down the spiral, the O-2 is consumed by AEROBIC bacterias, the same ones that are in your filter and make all the life possible. Somewhere around 3/4th's of the way down however, the O-2 levels diminish within the spiral, having been consumed by the aerobic bacterias higher up the coil.
[SIZE=-1]Now what? Well, now the ANAEROBIC bacterias begin to flourish, the very ones that feed on nitrate, not O-2! As the water continues its travels it encounters the main interior chamber of the cylinder. All those BioBalls are just waiting to provide area for more anaerobic bacteria to consume all the nitrate that wasn't converted inside the bottom 1/4 of coil. This is the "bank" that will allow the coil denitrator to continuously process more and more nitrate as it is produced within the display tank..[/SIZE]"
As we know Ammonia > Nitrite > Nitrate. What we are attempting to do here is cultivate a bacteria that turn the Nitrate into a gas that can escape into the atmosphere, rather than having to be handled exclusively by WC. In an O2 free environment their competition can't survive.