I am stumped. I haven't changed lights/bulbs. I have not run carbon. Besides the Caulerpa in the fuge for nutrient export, and B-Ionic for Alkalinity and Calcium, there's nothing else (besides WC's) that I do. All other corals look great, the very few SPS and a few LPS here and there all have excellent polyp extension/colors. No parameters seem to be out of whack. I use 0 TDS RO/DI water. Oh yeah, I did start dosing sugar a couple of weeks ago to reduce nitrates which has been pretty successful so far. But this frogspawn did this in a matter of 48 hours. Could this be related?