Everything that touches copper treated water should never be used in a reef tank again. So yes it is too late but you can minimize the damage by removing the copper ASAP with carbon andr cuprisorb. You will need to chuck all your sand and rocks.
So I have this opportunity to get a replacement tank from marine land since my tank is slightly leaking. I was thinking of just starting over and keep my fish in my qt for 6 weeks of copper treatment.
My question is can I just soak my sand and rocks in fresh water for a few days at high temp to get rid of any ich? Otherwise I'll just have to buy new sand and live rock.