Good luck! In regards to your comment about your LFS QT'ing their fish, I highly doubt they QT'd the fish to any hobby standard (30 days copper, 2 rounds prazi, etc).
I say that because for most LFS's, it's financially improbable to QT all incoming fish. Say they import 20 fish in a week and begin dosing copper (usually at half strength, NOT therapeutic levels), well the following week they just add more fish to that system resetting the 30 day copper requirement. Holding potential profits for that long typically becomes impossible to maintain.
It's not a bad practice, but I would never rely on the LFS's QT methods.