Quote Originally Posted by R_S_C
what other corals do you have in your tank...i've noticed hammers, torch and frogspawn sometimes tend to try and have chemical wars with each other. i had to run carbon to fix this.
Actually, these corals (euphyllia) do not use chemical warfare, but they are very agressive with sweeper tenticles. The xenia might have something to do with it, depending on the species of xenia. Eric Borneman's book has a great chapter on coral aggression; I'm sure you'll find your answers there.
Zoanthids and other colonial polyps will fight with euphyllia; I had one almost die from a battle with some star polyps. Usually there's visible contact between the corals that are fighting.

But, your Ca and dkh imbalance is much more likely to be an issue here, or maybe there is a water flow issue; euphyllias don't like vigorous flow.
Good luck!