I have 4 tangs (well all of my fish) in a 30 gallon hospital tank now treating with Coppersafe. The Ick was gone within about a week. The Coppersafe will kill the free swimming form of the Ick. So, if you dosed the tank properly, it's practically impossible to get re-infected with Ick once all of the initial spots are gone. What started showing up about 2 weeks after that were white spots on my morph tang. These weren't Ick spots, but a fungus infection. Last week I started treating with Maracyn and now all spots are gone. Look closely at the spots you are seeing. I'll bet they're bigger and puffier looking than the original Ick spots you saw in the beginning. That's one problem with Coppersafe is that it's use can cause secondary fungal infections, and it seems that the morph tangs are particularly succeptible to this.