I'll tell you what I think worked for me. I had a new tank and went through the same thing. Ich - fallow tank - reintroduce fish and more ich. Then I got two cleaner shrimp. Now when the ich comes around they go crazy cleaning the fish. My LFS
also said to feed food soaked for 20 minutes in garlic. This seems to really work for me. A couple of weeks ago I had the last outbreak. I had a sailfin Tang who woke up covered in white spots. By the end of the day the shrimp had him almost completely clean. Next day he was covered again, again the shrimp went to work, the third morning he again had spots but not as bad, by the end of the day he was completely clean and for the past two weeks I have no sign of any problems. The shrimp do allot of gill cleaning which I thinks helps as well.