[Stones]

I've had very good luck with my powder blue tang as it has never had a bout of ich even from day 1 and I don't QT any of my fish so long as they look healthy and come from a reputable vendor. I purchased my powder blue the size of a toonie from J&L and I've had it for well over 3 years now without any ich whatsoever.

As many of the others above have mentioned, I'd highly recommend running the biggest UV sterilizer you can outfit your system with. Contact time with the water column is very important so your flow through rate on the UV should be pretty low in order for it to be most effective. Sadly the UV emitters you will be adding to your LED build will do nothing for eradicating ich, they will only help your corals fluoresce more.

The use of UV sterilizers as a means of treating/preventing ich has been highly debated for years now in this hobby and mostly what it comes down to is personal experience. I was unable to keep any species of tang without them succumbing to ich prior to investing in a UV sterilizer. After I started running one, I haven't had a major outbreak of ich for almost 10 years. A few years back after adding a purple tang and a blue throat trigger to my tank, a few of my tangs developed a few spots of ich which I thought was strange as none of them had ever come down with it before. Turns out the bulb in my UV sterilizer had burnt out. After replacing it, the few spots of ich my tangs had never returned.

I've heard of similar success stories from many others in this hobby as well where the use of a UV sterilizer made the difference between keeping tangs happy and healthy whereas without the use of one, they were struggling with ich outbreaks every few weeks and after the addition of new fish to their system.

I also agree with Myka that powder blues and most of the tangs belonging to the genus Acanthurus do best in larger reef tanks where there is ample room for the fish to swim. I've seen these tangs do well in tanks smaller than 4 ft long however these instances are rarer and usually the tangs need to be relocated to a new home once they reach a certain size. Smaller tanks tend to stress out these fish more, weakening their immune system and making them more susceptible to disease and parasitic attack.

I hope this information helps your situation. Powder blues are one of the most beautiful and sought after tangs available to us in this hobby but are definitely not the easiest species of tang to care for.