I had and currently have ich in my reef. I tried every medication known to man that is reef safe. Nothing worked except keeping the fish very well fed. Went through about two ich life cycles before I found the stress causing it. My tank was dropping about 2-3 degrees st night. Threw two extra heaters in the sump. Once it was fixed the fish got over it. Yes ich is still in the system. I have not had it pop up in about 3 months.... Find the source of stress and keep them well fed. Soak the food in vitamins. I use garlic and vitamin C on brine shrimp twice a week.Is there a post that deals with having an up and running reef that has been infected with ich, that is not torn down or fish removed and treated. Post out break.
Once things are stabilized how to add new fish to the system? If you do the proper step of quarantining new fish treating them for possible illnesses but then add them to your infected system, how likely are they to still come down with the infection and die?