Yea, I'm with the above posts. I wouldn't worry. The main concern with Cu is people dosing directly in their tanks or using something that leeches copper into the tank directly over time. Like if you dumped a copper pipe right into your display tank. Usually the little bit that ends up in drinking water, if you were to use tap to fill your tank, is tiiiiiiiiiny, as the copper only interacts with the water for a little bit. If you put the pipe right in your tank and didn't do water changes where it was constantly in contact with the same water over and over day after day, then it might be a problem.

As stated though, if it's a problem, his inverts should be keeled over by now.