I was about to start a new thread with this same question. It was dong great for months, then I started finds parts of it in other places, including the refugium. The main colony went from look at that thing go to oh that poor thing in about a week, maybe 10 days. The parts that came off are flourishing once they find a place they can hang on to.
I did have a phosphate issue that it handled just fine. The only change since was adding actinic lighting. This seems more drastic a reaction than adjusting to additional spectrum. But I am new at this, for all I know that was the equivalent of running a lawn mower across it.
hoping somebody will say, oh it just does that, it will be alright before too long.