You may want to run an inexpensive air-driven sponge filter. Copper won't impact the bacteria population. It'll take a while for it to get established in your QT, so you'll definitely want to test for ammonia daily.
You could seed the sponge filter by running it in your sump or display for several days before moving it to the QT.
Hands-down, more fish die in QT from ammonia than from any diseases.
Are these fish in your display with others? The reason I ask is that if you have other fish left in the display other than the two you're treating, they also have ich, even if they're not outwardly displaying symptoms. It would be very frustrating to treat your two fish for several weeks, get them healthy, then return them to the display only to be reinfected.
Good luck and keep us posted!