Ugh, one more time, there are only 3 known proven treatments of MI. And ALL must be done in a qt. 1.Copper, instructions must be followed to a T, MUST be done in QT, very hard on the fish, 2.Hypo, to be done correctly it needs to be done with a refractometer, swing arms are to inaccurate and inconsistent, must be down in a qt, may take 4-8 weeks, and a lesser use transfer method, uses a ton of salt rodi and labor. Also DT will need to be fallow (fish less) for 8-10 weeks for MI to die off without a host (fish) to keep it multiplying. There are NO reef safe meds, ick out, ick cure, ick rid or any of the other snake oils out there. Ick outbreaks are caused by stress. Also do not do copper and hypo at the same time.
Fish get ich from stress, too small of a tank, too many fish, incompatable tank mates. Or bad unstable parameters. I personally don't qt or am sure I believe in it. I have 3 tangs all from different sources and have never had to deal with it, is it luck or a stress free tank, really hard to tell. Unless you are goingbto qt EVERYTHING, fish, corals, lr, or anything wet, then you are not going to keep it out of your tank. Just remember there are NO safe reef ich meds,: