so I've got a few different corals that tend to close up in "waves". Mostly my acans and zoas. One colony will close up for 1-3days, reopen, and then the colony next to it will close up for 1-3days. When they reopen they look super healthy and no worse for the wear. Nothing else in the tank seems to be affected. And not all of the acans and zoas exhibit this behavior. My levels are cal-425, alk-7.9, mag 1350, ph hovers around 8.