Well, may I say that it's not the greatest idea to have rock in a QT. No one should really tell you what to or not to put in anything that is yours, but... rock in a QT has a couple of problem areas, especially if it is live. Secondly, it is not at all uncommon for fish to have ich or other parasites in gills or other unseen areas. Flashing is usually a symptom of some kind of ailment, but not always. It is in a QT, so observe and depending on the qt enviornment you can do a precautionary hyposalinity treatment. I do not recommend doing copper if no visible signs are present. (copper is not a choice of mine anyway, but it's personal preference)
Most QT's are bare-bottom bare-bones system. It is function and financial qualities. Financial because it's cheap and easy set up. Functional because it's easy to break down if something nasty is brought into the system. Plus, treatment with rock in the system can have diverse effects on the outcome of treatment.
There is also speculation that it gives a place for the parasites to hide deep in rock holes and crevices where treatment isn't effective. If you treat with copper, the rock will absorb it like a sponge and leach it at potential lethal doses later.
