I used Cupramine in the past with great success. Do not use simultaneously with Prime.
Once done, use carbon to extract. Overload on the amount of carbon that you use to extract it, meaning the more the merrier. Salifert makes a decent copper test kit.
I've never had an issue of it not getting the job done. You need to test the copper level though. The only complaint I have is that it seems to be tough on some fish. I think I killed a Bicolor Angel with it and there's been other fish that did not tolerate very well.