"Unintended coralline algae bloom"
I don't get that term. I mean... you have no control over coralline algae - it just happens... assuming you have some in there to start with and your calcium levels are above 360. I'm not sure how you can have an "unintentional" one when you really can't have an "intentional" one.
High alkalinity doesn't necessarily mean you're headed for disaster. It just means that you might have some water parameter issues, as ccCapt mentioned, and that some corals won't do as well as others. Going from memory here, but I also think that Trachyphyllia (LPS
- open brain coral) don't care for high alkalinity.
What are your calcium levels? Are you adding any buffering supplements or using any 2-part cal/alk