Well, I've got mine growing under PC lighting. I noticed since I started dosing Pickling lime in my top off water, some of the colonies closed up and bleached. Other colonies are thriving. so, I don't know if some are sensitive to kalk or just the water chemistry changes that kalk introduces. (fluctuations in PH and alk, and so on). Some colonies are dieing off completely, others are thriving, the good thing is that since dosing kalk, they seem to have halted their reproduction advance on my tank. What I have is just perfect. It was growing new colonies on a daily basis. It has since stopped growing new ones.