I'm certainly no expert on polyps...or anything for that matter.. but when you're looking for growth, that, to me, means increasing the # of polyps. I did have a tank in the past that was primarily filled with zoo frags. They became quite elongated as well. I inquired on the zoanthid forum and many confirmed my suspicion. They were starved for light.
I see you have them way up high. What lighting do you have?
In general, I've found polyps to be very fickle. Some blossom, some wither and melt away. Sometimes you never really know what did it.
Not sure if this qualifies as help, or aimless rambling.
