In addition to higher calcium, you'll also actually need coralline algae. A great thing to do is go to your local fish store and ask them for a good piece of coralline covered rock. Take it home - make sure the lights are on and turn your return pump off (or any filtration you may have but leave the power heads running) - put it in the water and scrape it with a razor blade or brush it with a clean, new/unused, toothbrush. This will spread the coralline algae around your tank and allow it to grow much quicker. I'd leave return pump/filtration off for maybe two or three hours to let it spread nicely. Once you're done, just stick the rock somewhere on the substrate and leave it sit.