Cryptopure ??

[BCOrchidGuy]

Any idea how your Tang got the ich? Trying to treat ich in a reef tank is a difficult thing to do. There are a number of products that claim to be reef safe but you have to be careful. I've used products that say "Reef Safe" only to watch as polyps etc close up and Xenia and Anthelia receed and look like they've died. Most of it came back but not all of it.
Best of luck

Doug