I've heard it said the blue actinics help although marine biologists have found red coralline growing at 600 feet --explain that.
I have found that calcareous rock can make a huge difference. I've had traditional LR in my tank and coralline has been slow growing. I added 8 pounds of white branch coral that I collected and cured myself only a few months ago and the red, pink and purple coralline has grown at an amazing rate. I've also noticed that many highly calcareous shells I've added become almost completely covered with purple coralline in only a month. I've tried calcium additives and not seen any dramatic results on the traditional LR. BTW, rock that was buried or in the shade saw little or no coralline.