My grape caulerpa seems to prefer anchoring itself in the sand with it's roots while the rest of the algae rests on and above the sand. It grows quickly and is easy to harvest UNLIKE feather caulerpa which I would remove before it gets a foot hold if I were you. The razor is almost as easy to harvest and doesn't grow quite as fast but is more decorative IMO
. The grape will grow an inch or several in a day in good conditions. The amphipods, copepods, ostracodes, limpets, etc. enjoy the grape caulerpa more so than any other species of alga in my tank (and I have had plenty, ask Guy or Kevin).
Good luck and I hope it grows well for you.