a few confusing statements in this thread.
Hyposalinity in a quarantine tank is a proven method of dealing with Ich. The fish must remain in the qt tank for the duration of treatment usually 4-6 weeks. During that time you have no fish in the main display, just live rock and any inverts. This will let the ich cycle out of the display by starving it. (If you put your fish in there without letting it run the 6 weeks the ich will just reattach to the fish you must kill the ich on the fish and in the tank)
Do not use copper especially in your display as it will render the tank and everything in it useless for any inverts later as they cannot tolerate any copper that is absorbed by the rock or tank, sand etc.