I'm one of those people without coraline growth. I'm not the only one. Some tanks just seem to explode with it, others do not. I do feel that you need some live rock that has some good growth just to use as a 'seeder', from what I understand. Most of my live rock was only mediocre to start with and it never took off. Now, just recently, I have met up with two folks who tried the 'Purple up' product and swear by it, to get it going. It will take some time..I'd say you might see a difference in a month or so. I'd make sure you have 'some' coraline to start with, and then, maybe try the Purple up to give it a boost. Purple up, or anything else, won't help growth of something that is not already there. Beware of adding to many chemicals to your water though, to solve this situation. You may in fact end up on a roller coaster ride trying to get your levels right and screw something else up. Coraline growth is not a needed thing (albeit cool, to some). I imagine with good parameters, kept in line, that any growth will continue to increase with proper care. Just my 2 cents...
Bill