I'm using it right now (only stuff available in the city). So far it seems to be working but not as well as I hoped. I did take out my all my snails, shrimp, starfish and hermit crabs to be on the safe side. The ich seems to be held in check and has disappeared from all fish except the two tangs which where the original culprits in the first place.
The instructions are correct on the web site though, you cannot just dump it in and leave it. You need to watch the protein skimmer and empty it about 3 or 4 times and watch the fish as well. So far my opinion is about 50/50 right now, it's working but I'm still not sure of it.