[BoomerD]

I wouldn't hesitate to re-use a tank that had been coppered, but I WOULD scrub it out very well, and even let it soak in RO/DI water to help remove any traces. As Wit says, what little MAY penetrate into the tank, (would be very minimal IMO) should pose little to no problems. As for any porus material, rock, sand etc, I would NOT try to re-use that in a reef. Better to use that in a FOWLR where whatever leached out wouldn't be much of an issue.