I don't know if zoas grow faster on glass, but I know they grow pretty fast on marble. I would mount frags of zoas or anthelia on 1 inch marble squares, then put them on my frag rack with empty tiles in between mounted ones. Then they would grow onto the empty tiles I would cut the stolon, and put another tile in between. In no time, 1 frag became 2, 2 became 4, 4 became 16... Pretty soon I was giving away frags of blue anthelia with every purchase because I couldn't sell them fast enough.