Only 2 sure fire ways to get rid of ich, copper and Hyposalinity. Copper is deadly to inverts and detrimental to fish so I suggest hypo. Try the disease/treament forum and see what Terry B or Beth says.
there is a product out there called kick ick it works wonders it has no copper in at what so ever the first time i set a saltwater tank up i had to use it a couple different times just cause i didnt know what i was doing i was rushing and not checking my water and the balance was not right