No clue really, could’ve been a lot of different things,
It was touching several different Coral, could have been a flow issue, could have been minor alkalinity swings, could have been minor temperature swings,
Probably a combination of everything,
I drain the tank,
Only give them a few inches to run around in,
Stressful on me, but seems less stressful on the fish.
And the tank still gets hit by havoc! Haha