or too low. everyone readily adds calcium without tending to the alk
. not saying you did this, but that would be my first thought.
that said i grew a birdsnest from a 1.5" frag to a softball sized colony and fragged it multiple times. ones day i cut a small piece off of it for a friend and put it back where i got it without removing it from the water. the next day it was completely dead.
i didn't change any parameters in my system, so i attribute it to what was residing on my hands at the time.
colony at it's best-
the day after fragging-