Hey Brad,
Sorry to hear about the loss of your fish buddies. Hope the survivors pull through. You may want to try a freshwater bath as it will clear them of any parasites and make their time in the QT shorter. I would also recommend a UV on the tank to help clear any free swimming MV.
Copper is poisonous. You just kill the parasites faster than the fish as they are smaller.
If you are going to let the tank be fallow for 6 weeks then I would recommend adding Ammonium Chloride to keep the bio filter going. Otherwise you will get an ammonia spike when you put the fish back in and the acros will hate that.
Cheers,
Tim