I've noticed that my live rock goes through spells of good and bad. At the store the rock was beautiful and full of purple algae, and when I got it home i had the normal die off but it never got back to where it was at the store. basically i've just noticed my rock goes through spells algae growth and then die off, and i dont why. its not normal is it? I was hoping by now that the algae would have spread to the parts of the rock that werent already covered, but i'm lucky to keep the algae where it was originally. does anybody know what might be going on with it, and is it a real problem or sign of something bad thanks!