One thing I got from the documentary is about the coral bleaching. I know that when I coral bleaches, the zooxanthellae leave the coral and the coral is still alive. The documentary said that, the zooxanthellae can return. You see, I bleached my coral back in July, when I switched to new more powerful lights. My acro had purple tips, but it is now all white, it's still alive, but just white. The documentary (if I understood it correctly)says that the algae will return to the coral, from what I understand they are floating around the water column. In our closed aquarium, if a coral bleaches, what are the chances for the zooxanthellae to return? I am assuming zero, because my acro is still alive, but it's totally white.