I have a par reader. From my experience: in general softies tend to do well from 100-200 par, LPS like 200- 300 par, and sps like to be in 300-500 while some sps respond better to 500+ par. (Chalice like lower par) all coral can be accustomed to higher or lower par to a certain extent. If you see your coral bleaching it could be a sign of it recieving too much par, if the coral is turning brown it could use more par. If you want to know for par numbers for specific coral search for "coral par numbers" on google images and you will run into a lot of pictures where people have posted thier par numbers and you could see the coral they have in the tank. (Meeleev reef tank picture comes to mind)