Try getting rid of it. Murphy's law will dictate that you end up with more than you started with.
Seriously, scrape some of it off the rocks you have, it grows back with a vengence for me. I use half a dozen urchins to do the scraping for me since I'm a lazy American.
I forgot to dose with Strontium, and it started to die off. I added it, and the coraline grew back with a vengance. I noticed that iron has helped as well.
I battled coralline for a long time...because I was too lazy to dose everything I needed to. Strontium, magnesium, etc, etc. Once I hooked up my CA reactor my coralline took off like never before. It is the lazy mans way to get good coralline growth. I am not saying a reactor is for everyone, but I travel and it sure does work for me!