Some pics would help.
Are your tangs rubbing against anything? Is their breathing normal and are they eating?
To regurgitate what others have shared on this forum with me, Ich is pretty normal and if you water parameters are correct and your fish is healthy, it will just go away. Bump your temps up to 82 or so to make the ich cycle a little faster.
I wrote on
article on my blog summarizing what I learned from various folks on here.