I'm planning on having a euphyllia garden on the top of a large rock but would have lots of empty space on the base of the rock and the sides. I was wondering if I could fill it in with zoas, I don't know if this would work but I was thinking that this would keep the zoas contained as they can become pests and overgrow their place but they wouldn't be able to grow anywhere but on the base of the rock as if it tried to go up it would be stung by the euphyllia and if they grew onto the sandbed it would be easy to remove. Would this work or should I look into fragging the zoas to stop them becoming overgrown?