and FYI, starting over with new rocks and sand may still not be enough to keep inverts, copper can be absorbed by the silicone of the tank as well, only to be re-released when the tank is set up again.
Rule number one of saltwater / reef keeping:
NEVER dose the display tank with medications, this is what a quarantine/hospital tank is for
Hopefully you didn't dose your display tank with copper for a new fish