I'm making the assumption that that is coralline algae
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Sent from my iPhone using MonsterAquariaNetwork app



Have you added any coraline to your tank, because you have to have it to get it. if you purchased any of your rock live or sand live chances are that there were some spores on it. if you got it all dry, you have bacteria coloring up your rocks. Once you have the coraline in your system, if you want it to grow quickly all you need is to keep your calcium up around 400 or better and keep phosphates down. purple up is a scam, it is really just powdered aragonite.
If you really want to see that coralline take off use a 2 part calium additive... Purple up is ok for a small tank like a nano cube but for anything else it's kinda useless