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Sorry your first post was with a problem. Unfortunately I have not used Coppersafe. I believe it is one of the least desirable copper medications to use. Please read through this post: Copper - Treatment, Use, Problems
The fish are moved to a quarantine tank (QT), setup like this: A Quarantine Process (step-by-step). The medication is added to that water.
If you're treating for a suspected Marine Ich problem, then you should also read this: Marine Ich - Myths and Facts
Hope the above helps!