Hospital tank or QT tank is the best method but if you don't have one you could try treating your food with garlic. This does not rid your tank of ich per se but is effective in building your stocks' immune system which in turn helps your fish fight disease and parasites. Some will disagree with the idea it does not rid your tank of ich, me being one of them. I have had two battles with ich and to date have lost only two fish. Go to the grocery store buy a clove of garlic, crush it up as much as possible and let it soak in RO water over night in your frig. Then when you feed your tank let the food soak in some of the garlic juice for 30 min to an hour, drain the juice and feed normally. I keep a container in the fridge and do this everytime I feed my tank while others do it less frequently. Some say doing it once a week is enough but I figure if once a week is good 7 days a week must be better. Very effective for helping treat minor out breaks of ich. Hyposalinity is the only way to completely rid your fish of ich and since you have corals the only way to do this is with a QT tank. Good Luck.