Quarantine Tank

[gregzz4]

I think the consensus of a fallow tank is past 9 weeks, and some even go 11, just to be clear of everything

Your QT will be dictated by the size of fish you put in it
Longer tanks are needed for swimmers such as tangs and rabbitfish
A 20g is fine for small guys under 2"

I'd stay away from copper as it shortens lifespans

Put them in the QT and monitor them for 6 weeks
If you like, after they are eating for the first week, use Prazipro as suggested, but after that, if it ain't broke ...