About 1 month ago I placed my first corals in a 40 gal breeder, some montipora ect. All have been doing great until about 3 days ago. I noticed on a birdsnest coral I had a white patch on the bottom where it's attached to the rock. Next day it's quite larger. Today it is 2x the size. Noticed my alk is around 15dkh. Not good. Could this cause a sudden change in the coral? Is this Bleaching or dying coral?