Hi everyone, I'm new to this forum and a little late to the thread, but I'll post anyways.
When I bought my first sun coral, I built it an awesome cave in my live rock to shiled it from my lights. Some people think this is critical since sun corals aren't found in direct light in the ocean. I, however, soon discovered that this coral's feeding schedule and requirements make the cave idea irrelavant. I wasn't feeding it enough because it was inconvenient. I decided to feed it more and worry about light less and my sun coral thrived (past tense because I gave it away).
I had put it front and center under direct light and it eventually got to where it stayed open for about four hours a day.