Copper in quarantine?

[Reef Pilot]

Once I had my water down to 1.009 (the magic number), I never changed it again, until I was raising it back up. For that, I used display tank water (from water changes) to get it back up. The advantage was that the new fish were fully acclimated to my DT (their ultimate destination) water when they were ready to be moved.

Of course, I checked water params in the QT the whole time. And be sure to use an accurate refractometer. Those swing arm hydrometers are totally inadequate for this purpose.