in the process you will get all kinds of these questions while we try to figure out what is going on wrong and how to turn it... and we have all been through it
Right now age of tank since cycling, water change schedule, light, pH Alk, N and P and will be a good starting point
We need a full set of water parameters as already said, but it could be something as simple as a temperature fluctuation, flow, something bothering it, sometimes it just happens and it can be very frustrating
Dont see what is reffered to as bleaching however when coral are unhappy-bleaching-pouting, it us due to stress . . Stress from too much light and water flow and lack of nutrients.
You were asked about parameters. The typical parameters for your tank are posted below. Moderate light and water flow are key for LPS coral.
Welcome to R2R , this is a great community and help will always be given provided that you give as much information about your tank and its current situation so an educated guess can be given.
Welcome to R2R. Good advice given. More advice will b given wh you give more info. Lots of knowledgeable and helpful people here who will support and advise you when needed.
Welcome to R2R! As others have said, we need more information to provide any meaningful help. How long the tank has been set up, basic water parameters and a little detail about the tank set up at the least.