I have 4 monti frags - 3 are caps and 1 is a digitata. The original corals are bright green and dark red, but over the course of a few weeks, all my frags have turned to an ugly brown. The two oldest frags are starting to encrust their bases, all of the frags regularly have all of their polyps extended. I have a 30 gal tank with VHO lighting. The frags are all in the upper third of the tank near the surface. Negative on the nitrates and calcium is about 500. I drip kalk and the salinity stays pretty close to 1.026. I have a few mushrooms and zoas, xenia, colt coral, and anthelia frags in the tank. No fish. I run carbon in the sump continuously. Anybody have any thoughts on why they all turned brown? Is it temporary? Too much/little light?