I think this obsession with copper being like polonium 210 is a bit much on this forum.
If you think your tank has copper, rinse it through a couple of times with tap water, and then once or twice with RO. Having had a tiny amount of copper in a tank is no great problem.
My sump on my reef has previously been used as a FW whitespot treatment tank, while the frogfish tank also plumbed into the reef's water was used to treat SW ich. None of my shrimps and corals have started dying just because there was once some copper in the tank, and it would appear the copper hasn't hid in the silicone seals waiting to jump out and nuke the inverts at the first possible chance.