Can any rock be base rock?

[eli@fijireefrock.com]

you need to have calcium carbonate rock.not any rock will do.it might leach and have some traces of medals,..
choose a light with lots of micro and large crevices in the rock as later it will be a home for all living good bacteria for your tank.
when choosing live rock make sure its got no algae no aptasia no bad crabs and the list goes on,not to scare you.best bet for live rock grab it from a trusted person with and older tank that you know has no complaints.