I agree that it will take a little time. In both my tanks I was seeing good growth in 3 months. I am one of those that does not suggest using any of the "acceleration" products like purpleup for coraline growth. You really need to focus on not adding anything to the system unless there aren't any other options. Also, you should not dose something if you do not check it's levels - such as iodine or strontium, even calcium for that matter.
Can you describe your system.....