I have 2 regal blue tangs who appear to have ick-a few white spots which they are itching. Other than that they are fine, swimming around and eating well. My question is-I have already QT them once for ich, is it possible for them to get it again? I have added cleaner shrimp to the tank, will they help rid the tangs of ich? I've heard/read that ich is always present in the tank, but how do I prevent them from getting it every other week? I check my chemicals every week. Nitrates/nitrites/pH/alkalinity all within normal limits. Anyone have any suggestions?