Powder Blue has white spots GRRR

Have to 100% agree with this lost one of my recently to moving him to a QT My solve to this problem was just that move to the QT. It was a blue hippo and yellow tang. Yellow did not make it the hippo is smart he lets the cleaner shrimp handle there business and the yellow did not. So what I did was pickup some more cleaner shrimp for him. With a UV sterilizer to control the population of crypt. The blue tang was treated for 2 weeks with copper then put back into the DT and still has ick but not as bad. He is happy eating now and loves the fact that he is back in the DT tank. Starting to believe that no matter what the best way to control it is just to let it take its course and see what happens. Out of all the fish I had only the tangs ever got it. good shrimp + Smart Tang = Healthy tang IMHO so there is my 2 cents