I would agree with the above post, 1-1.5 weeks more of copper and evaluate. I have personally gotten away from copper and only use CP. Very very happy with CP. For starters it is not a poison for the fish. Very effective with low risk. I would definitely do copper for a while longer than evaluate. If you still have signs of a parasite then I would switch over to CP immediately. I have been talking with Humblefish about his experiences over the years on multiple fish and CP. He has never had a fish treated with Rx quality CP and have parasites after two weeks of treatment.