Maintaining proper levels of calcium, alkalinity, and magnesium will greatly aid coralline algae growth.
Purple Up is just an overpriced way of trying to do that. The individual components can be added separately for much less, while allowing one to add only the chemical(s) that are needed.
Lighting amount isn't quite as important for coralline growth. The colors of coralline that grow tend to vary depending on lighting quantity and quality, though.