I used the product "kick ich" in the past.
It seemed to work great, no coral deaths. Been a while now since then, but the product, I assumed worked as the tangs made a good recovery, or they could have fought it off themselves. No way to really know.
I would watch the other fish, as ich can live for up to around 30 days or so, from what I remember about it.
Hyposalinity and copper are methods to use ONLY in a QT. Reefs are very susceptible to copper and changes in salinity (especially starfish and many corals)