Little red bugs

[Aquattro]

symptoms can include loss of color, genral paling, and little to no polyp extension. They do not affect anything other than acros.
You can see them with the naked eye as tiny reddish dots moving quickly across the tissue of the coral. They are really small and much smaller I think than most people imagine. Many people have posted with certainty that they do not have them, when I know they've aquired corals from affected tanks. This leads me to believe that they aren't looking hard enough.
Go to reefcentral and search the SPS forum for red bugs. You'll find tons of info, pics, etc.