Hi all, About 3 weeks ago, I noticed some bleaching out on my montipora. Just a few spots that seemed to follow a line going lengthwise up the monti. About a week after noticing the damage I removed the coral and inspected it, hoping to find nodibranchs or something else obvious and unfortunately found nothing. I've also tried dipping the coral, hoping there was some pests on it that I just couldn't see, but that did not seem to help. Since then the bleaching has gotten worse, following the same line of damage and at the same time growing thicker. Much of the damage has started to brown out. The montipora had been in my tank for a good 6 months before this started. Any ideas what could be causing this kind of damage? The photos show how the damage has progressed week by week.