I've had problems with too much coralline, actually grows over my corals and has encased everything in my 125g. I just keep the water parameters in order as far as calcium, alkalinity and magnesium.
I did however use a bottle for for a few weeks of purple up in my 90g and my cube. I used a 20g as a control.
Believe it or not the purple up tanks actually showed ALOT of coralline growth versus the 20g that had no purple up put into it. All three tanks I used for the experiment had a small amount of coralline already so the tanks did have some to begin with.
I am not saying that purple up is a miracle solution for coralline but it did help, not sure if it was the cal/alk
/mag that is in the bottle that wasnt in sufficient amounts in the tanks but I really saw it work.