The fellow on RC who is getting dino's (and wants to black out his tank), is getting them because his small reflectors are only covering 1/3 of the screen....
http://reefcentral.com/forums/showpost. ... count=2135
So he has 1/3 the filtering that he thinks he has, which leave nutrients in the water for the dino's to grow. And since the nutrients in the water stay high, the screen stays brown. Blacking out the tank will just make this worse because the dino's that die in the display will put even more nutrients into the water, and make the screen stay brown.
The fix is to not to black out the display; get reflectors that cover the whole screen; and probably increase wattage until you start growing yellow, then cut an hour or two of light (more watts with less hours, is always better that more hours with less light).