If you put in new live rock the copper in your tank will only kill it.
It would be a good freshwater tank.
You might try running polyfilter nonstop for a few months and see if that can get it, but any snail you put in there until you have found something to remove the copper [which is evidently in the glue of the tank, now: this happens when copper is dosed in a tank]...any snail, crab, etc, is going to die. So will bacteria in the rocks and sand, impairing the tank's ability to support fish, which themselves don't quite thrive in a coppered tank.
Offer it on e-bay as a reptile tank: it would be safe for that.