Coral burt from too much light?

[quaqa88]

How can you tell if a coral is being burnt from too much light in the aquarium? I have a green star polyp colony in my 10 gallon nano reef and for the past month it has been acting strangely. The first sign of abnormality was when I woke up one morning and every single polyp was retracted. It took a little more than a week for the polyps to come back out. When they did finally come back out, there is one section on the right side of the coral that the polyps did not want to come out, and it stayed bare for another week or so. Now the polyps are all out, but that right side of the coral is still much more bare than the rest of the coral. Also, if you look closely, some of the polyps have blackened and seem to be like little black stumps. I do not know what is going on with this coral. Over my 10 gallon aquarium, I have a 108 watt power compact fixture, with two 36 watt 10K bulbs and one 36 watt actinic blue bulb. I know that green star polyps are better in a lower light environment, but is there too much light on the tank? My other corals are fine, but could I be slowly burning my green star polyp?