I caught an issue of a friend's euro magazine that did some conclusive analysis and testing of the addition of sulfur in closed systems. It brought the nitrate in a 300gal shark tank down close to 100ppm. They were dosing it, but H and S makes a sulfur reactor, more less a nitrate reactor, but you don't supplement with bacteria additive, etc. like the ones we have seen in the states where you more less just grow a bacteria culture to eat it. This is a whole different approach with the same idea focused in mind.
I forget the chemistry behind it, but the sulphur bonds with nitrate forming nitrogen gas, leaves behind another sulfur by-product, I think sulfur gas, not sure. I'm no chemist and the article was a bit lengthy, so the above data could be way off. Anyhow it sounded like a very good idea. I'm trying to get my new reef up and running at it's very best and was just thinking about one of these.
I like the H and S. I think Schuran and Knopp make them as well.