I was never able to keep a powder blue until I added Ozone to my tank, I had lost several over the years to the Ich. When i built my newest system i added a powder Blue and a Kole Tang. I had been unsucessful keeping both of these fishes in the past. Naturally, after I added them they broke out with Ich. I added an ozone injector to my skimmer and the ich cleared up in a couple of weeks. Since then in the last 4 years I have had two more out breaks of Ich after adding new fish to the system. Each time, I put the ozone back on line and each time the ich has cleared up with no losses. Lots of people argue that ozone doesnt work. I have had three outbreaks of ich in my tank and each time I applied ozone and esch time the ich went away with no losses.