My LFS started running a couple of them, and I think it IS a Ca reactor. He's been playing with one, and now runs it with bottom half sulpher, thin foam divider, top half Ca reactor media. There's an ORP probe in the top, and the ORP is controled by the output flow. It's putting Ca into the system, and dropping the Nitrates also. He's super horned up for these things, think's they're the cat's a$$. He says that once the Nitrates are down to 0, the output will be almost fully open, then gets opened all the way so the bacteria don't die, they may diminish, but continue to pull Nitrates as they're produced. AND the unit has an impact on Phosphates also, not huge, but noticeable.

Pansy-Paws, Where do you get your sulphur media from? Wine shops like posted above? or somewhere else?

I thought this excerpt should be posted here:

When dissolved in water, the smell depends strongly on pH (which determines how much is in the volatile, hence "smellable," H2S form). Humans often can just detect hydrogen sulfide odors when the concentration is above about 0.029 ppb in freshwater. In seawater at pH 8.2, where only 6% of the sulfide present is in H2S, this odor threshold is likely higher, perhaps on the order of 20-fold higher (0.6 ppb). Fortunately, that threshold is below the lethal limit of many aquatic organisms (usually above 5 ppb; sometimes as high as 50,000 ppb), so odor often can be detected by humans before hydrogen sulfide rises to acute, lethal concentrations in reef aquaria.

Taken from here:

H2S & Reef Aquarium:
Randy Holmes Farley

http://www.reefkeeping.com/issues/2005-12/rhf/index.php

I got my sulphur media from J&L ... in the form of Caribsea LSM. Never thought of wine stores at the time, probably much cheaper if you can find it.