Waterkeeper, thanks for the advice!
The copper was several months ago, and I have done many, many water changes in the QT since that time. So, copper levels should be pretty low, but I was definitely nervous about it. I will try the vinegar technique. The QT is 20 gal - so, can I add 19 gal of freshwater and 1 gal of vinegar for the soak?
BTW - nice kilroy reference... not where my screenname comes from, but I can definitely appreciate the reference.

I was actually in a play many, many years ago where my character was named Mr. Kilroy. Have used the name ever since.