Is that alk in dkh??? 15 dkh is waaaaaaaay up there.I would bet if thats in dkh thats what killed the trumpet head.Natural sea water is in the upper 7's to low 8's.I would address the alk if it was me.Good luck
That is DKH, why would it just affect this coral and not all my other LPS, including a hammer coral. I'm open to suggestions on how to lower it.