Ahem...I have a post asking foir a green acro and another asking for a yellow acro specifically so that I can try this out. Mostly so I can see, based on his methodology, whether I am treating my corals properly. If the yellow is nice and bright with no tint of green, then I know I have that basic level of water chemistry correct, then i move on to the next color to see if I have that one right.

I kinda think it might be hooey with a bit of science thrown in, but, if it turns out to work, it really might be a good way to keep track of your husbandry techniques.