Zoa/palys: on rock or on sandbed?

[mrhasan]

I have heard mixed opinion on people succeeding on growing zoas/palys on sandbed while others fail and prefer rocks. I myself am experiencing that my zoas and palys are not willing to expand into the sandbed but rather is either attaching itself to the other zoa/paly's tile or just packing up on the small rocks/tiles (yah Denny's patented tiles :P) they are attached on. I am keeping all the zoas on sand bed now but thinking of gluing them to rocks.

Would like to know what others have success with: rock or sandbed