I've had great luck with Purple-Up - no alk problems, and it helped raised the CA levels when I was using Instant Ocean salt (which always had very low CA readings).
I have a tank that's less than 3 months old (relocated an existing tank into it), and I've got tons of pink and purple coralline all over the glass. It's not covering everything, but one side has a solid growth of it that's about football sized - right where the flow from a powerhead hits.