Guys, i think that purple up is another one of these supposed "wannabe miracle cures" in a bottle.
If your water conditions are good enough, the corraline will come. Don't look at Marco's old tank and say that the purple up performed miracles. Marco's tank was a very mature and stable setup, with good supplementation of minerals etc. In this kind of system obviously the corraline will come thick.
I would rather not go for a miracle "one off" bottle, but rather keep a keen eye on your parameters (mag, cal etc), and have patience.