http://reefcentral.com/totm/2001-04
The above link is the only pic left of my former tank. You can see the star polyps have climbed the acrylic overflows. The mother rock on the right was encrusted in several layers of mat & polyps, some places several inches thick.
The secret for me was always good light, from at least 250w halides. Most of that growth came from under a combo of a 400 & normal output bulbs and then a 400 plus a pair of 175w 10K bulbs.
I agree with Shao, as mine always loved good water flow. They looked limp and not healthy under less.
Star polyps also consume decent amounts of calcium, so attention should be paid to proper levels.