Just curious, but where did u get that info. I have been using Tropic Marin since i started in the SW
side of the hobby and i love it. If it does add copper it is in such a tiny amount that it doesn't matter because i have had many inverts with no problems and my friend runs his reef with Tropic Marin also with no problems. It is by far the highest quality salt out there.
For the most part i have found from personal experience and the experience of some of my friends that when it comes to this hobby you get what u pay for. I am more than happy to pay the extra money for a better product.