it is an old german calcium additive that has been used for years. it works by adding calcium/dKH and increasing your tank's pH. the rapid increase in pH and alkalinity on the polyps will kill them. but don't do too much as it will jack up your tank if you're not careful.
My brother just did a complete overhaul to his tank and had to eradicate a bunch of polyps (star, button, even some shrooms). I gather that by taking out the rock and placing it in a spereate container with a much greater salinity (not sure exact amount) he was able to kill the polyps and still keep the coraline alage.
For most of my rocks that would be a pain in the rump, but it was a one time deal that did the trick correctly.
J.
It depends on the polyp type but i had a huge problem with polyps and under the advice of a well respected LFS owner i purchased several perper mint shrimps.
Nothing happened immediatly but about three weeks later i noticed that my polyps were disapearing. i still have the shrimp its been about a year and i have nver had a problem with polys again, they also dont seem to be bothering i do care about.
They do only eat cirtain types of polyps though i forget the names i will find them and podt them.