Islands for coral?

[The_Skrimp]

I’ve seen people recommend creating an island off of the main rock work for things like green star polyps or even zoanthids. How much area does an island need around it for it to be pretty safe that something like GSP won’t attach itself to the main rock work? Is a couple inches enough or should I do more? I’d like to eventually have a GSP colony and a zoanthid rock.

 

[Hemmdog]

3 inches or so should be sufficient.

 

[The_Skrimp]

Awesome thank you!