If you have NO coraline algae at all, you may never have any. The best way to get a lot of coraline algae on your live rock is to make sure your water levels are all where they should be, and make sure you are supplementing with calcium to keep your calcium levels at 450ppm.
Then get some live rock with a LOT of coralin algae and place that rock close to a strong powerhead, so it gets 'blasted' with the stream of water- that way it will spread faster. Dont expect your rock to all get purple in a few weeks- give it 6 months or so to spread. YOu might not notice- so take a photo once a month- or every couple weeks.
We had a disaster with some 'distilled' water that wasn't, resulting in the death of about 75% of or coraline alage-- 3 months later, about 50% of it is back. it is a slow process, but worth the wait. Given the right conditions, the coraline algae will eventually cover all your rocks, powerheads, etc.