EXVISOR13,
Also keep an eye on your water temp. I have noticed that water temp, especially this time of year, has a tendency to cause ich outbreaks. Its just another source of stress. Not only is there an issue with the temp, but as temp. goes up, the amount of oxygen in the water goes down. There's not a lot of oxygen in salt water to start with. I think O2 saturation is about 7 ppm in SW and that is at at really cold temps. 4 ppm is about typically for where we run our temp. Even a small decrease can be a problem.
Tangs are really high metabolism fish. High metabolism means high oxygen consumption. I believe this is one reason why Tangs may be more suseptible to Ich. I'm not saying that temp is the only reason that Tangs have Ich outbreaks, but I will say that the only tank wide outbreak I ever had was the result of a temp. spike and it wasn't just tangs that had it. Temperature also has an impact on the Ich parasite's life cycle.
Gary
125 SPS, 75 gal. LPS/softie reef, 9 gal. Nano