disinfecting corals

[George]

None of proven marine ich killing medicine/method is coral safe (well, except tank transfer but that is a different topic), i.e. they will kill your coral.
If you are serious about keeping ich or any parasites out of your DT, the best method is to set up a frag tank. QT your coral and invert in your frag tank, no fish. Fish should be QT'd in a separate tank.