You also need to determine what triggered the ich in your display. Have you been having temperature swings more than 4 degrees from nit to day? Did you recently add any fish? Try to pinpoint what happened that caused the outbreak. Ich is triggered hormonally so if you have stressed fish, there is a greater chance of triggering the attachment stage of the parasite cycle.
There are lots of methodologies to treating sick fish. Copper by far works best because it immediately kills the parasite with minimal stress to the fish. Do some research before starting any treatment. If your fish are still eating, there is a good chance they can pull through. If they are still eating, adding a vitamin supplement/garlic additive/medication can be very helpful. Take your time when QTing fish. Just like the rest of this hobby, nothing good happens quickly.
Cheers~!
Jon