hi aquarium girl, I can tell you have done some research because you placed that sun coral under a ledge but just incase someone else out there didn't know, I thought I should say it anyway - sun corals although very beautiful are all animal and as such are a high mantenence coral. They require frequent if not daily target feeding. Feeding hats are the most common way of doing that, but where you have it may make that task a little more dificult. I know they say to put them under ledges but light really doesn't hurt them because a healthy colony can resist algae growth and frequent feeding and moderate current will keep them healthy.