Copied from Wet Web Media a site maintained by Bob Fenner author of the Conscientious Marine Aquarist.
"I'd try to remove even more copper by the use of absorptive media such as Poly Filter, which changes color to show that it's absorbing the copper. CupriSorb by Sea Chem is another excellent media to help remove copper. Copper will continue to leach from substrate, rocks, and the tank itself over time, but the continued use of the aforementioned absorptive media and regular frequent water changes should help dilute the remaining copper to even lower levels. I'd employ these methods for several weeks, then, after continued water testing indicates undetectable copper levels, begin slow and judicious stocking of invertebrates in the system. Proceed with caution.
You can try this.