General Reef Discussion
Mystery dead spot on a chalice.....
....from lights?
....from a pest?
....from a fish nip or hermit or shrimp?
....from water chemistry?
....from spot feeding?
....other?
Background:
> My lights is a 250w 20k MH light about 3 months old - 6hr light cycle
> I have several hermit crabs, a fire...