It's definitely stressed. With your parameters, I'd be far more concerned with the 5 Kh, than the 380 calcium. That is extremely low and could be the cause but, some questions first:
What is your feeding regimen?
- how often, what kind of foods, vitamins; if any
How long have you had the coral?
- same tank as always, same spot?
Flow and lighting
- how much flow is in the tank and is any directly at the dendro
- what type of lighting and how many hours? Looked ok in video but want to be sure
Parameters
- you checked ca&kh which is good. What are your nitrates running? Any ammonia or nitrites? If the coral is new, you may have some built up from feeding it
- these corals are very sensitive to high salinity, over long periods. Check that and calibration of refractometer
If the dendro is eating, feed it daily! They are very tough corals and can come back from death's doorstep. Mysid is good, Fauna Marin LPS Pellets; also good. If you have, or can get, Selcon; soak every food in that, for now. If you can't pick Selcon up locally, grab some Zoe. Also very good and usually easier to find.
Let me know the answers to those questions and we'll see if we can figure this out. Still in good shape and if we figure it out this early, it should be a speedy recovery. There are other possibilities but these are the most common issues. If you'd like to pm your email, I can send mine in return, which may speed up responses
