One has to remember that coraline is an algae and requires the same conditions to grow that any other algae needs...nutrients and light. It just happens to be more desirable then any other algae and is therefore a good way to soak up nutrients in a tank.
And corraline not liking bright light is just a myth. It won't be the nice dark purples and reds but the pink stuff grows like gangbusters only 6" under a 250w 10K DE MH
and just in case there are people out there that don't know it yet...I HATE coraline algae