I have only had mine a week (from NorthEastCoral.com), but it seems to use both light and food for nouishment. I have mine on the sand in the front/center of my tank. (I think it is 5 heads.)
I fed a mix of DTs, VitaChem, mysis, and cyclops. I used a long baster to gently spray it and it sucked it all up.
Dentoid has a nice large colony and has for a little while. Perhaps he can share his secrets of succes.