Stability is my question due to tank age. The tank may seem stable on the big 3, but things we cannot test are more than likely not stable. This and the lighting may be the cause.size tank ? interceptor? @Eagle_Steve ??
One has to remember, 300 par of mostly white and 300 par of all blue causes the zoo to react differently. This coupled with new tank instability can cause all kinds of havoc with sps.
The sand and water from the beach doesn’t bother me that much. I bring stuff back from Florida all the time and throw it in tanks. Although on a new tank, it could have shocked some things, but highly doubt that.