My Carribean Tang had Ich and I used a product called Cryptopur.
http://www.sera.de/English/autoframe.../News/news.htm
It cleared up the Ich problem in 6 days without hurting any of the corals. The only casualty was my cleaner shrimp.
It turned the water a disgusting copper color and the zoos all closed up for the week but are now responding fine.
This combined with garlic may do the trick.
Good luck.
Jim