Contrary to popular belief, most LPS
corals do not like excessive light. They do best in moderate to low lighting. Bleaching is actually quite common in these species as well as short tent plates. Many assume when the color fades it needs more light when in fact it needs less. Darker colors (browning) would mean not enough light.
Best suggestion is move the corals to a more shaded area out of direct light. With PC
configurations, the center areas of the tank will be brightest so moving them towards the ends of the tank might just do the trick. If not, then partially under and outcropping.
How's the chem?