<a href=showthread.php?s=&postid=8438694#post8438694 target=_blank>Originally posted</a> by Project Reef
The dead base rock, 'may', pose some issues.
Technically, if you were to use completely cured, established live rock, brand new rinsed sand (or no sand), and freshly mixed saltwater (or NSW), you could put fish in it in a matter of hours without any issues what so ever.
Generally speaking though, it's good to wait a few days, if for anything to simply let the water become crystal clear.