My tank is a blackback and I have little staging area thats directly under the MH's. I make sure that the background is kept clean coraline algae and doesn't have any rock outcrops. It's a very big area, maybe about 5" in diameter and has a shelf thats about 3" around where I can position the corals. I have to move a coral to the area, wait for it to open and repeat for the next coral.