This worked for me treating my tang that got ich.
I used both Microbe-Lift Herbtana and AquaPharm Cure Ich at the same time. After the 4th day, number of "white spots" on my tang visibly reduced. On the 5th day, tang looks totally "ich-free". However I understand that ich can remain active in tanks for a long time. The instruction states to dose for 10 days though.
http://www.microbelift.com/products/home-aquarium/reef-and-marine/herbtana-reef/
http://www.aquamarin.com.sg/productsDetail.asp?productid=266
My tank contains SPS frags, Zoas, Mushrooms, Clove polyp, Tube worm, Starfish, Shrimps and snails. All inverts and corals remain unaffected by the medication.
Read the sticky thread in this forum, there are many articles on curing ich. Again, the only 2 recognized ways (scientifically) to cure marine ich is either using Copper or Hyposalinity treatment.
Hope this helps.