If you are treating with copper then no. I understood you to be pausing the treatment till parameters were in line. If that is true then the carbon will help pull copper out and clear the tank. Then your water changes to bring everything else in line with possible bacteria added.
For what its worth, I use seachm stability in my QT to help get it going every time. I haven't lost a fish doing it this way yet, no stability then yeah I lost fish. I keep my fish in a QT/ observation tank. You can run seeded rock or whatever you want. Any signs of infection will show, but then they can be treated after everything is removed. This gives you plenty of time to get your filter pads loaded with biological filtration from your DT. Remember that the count down on whatever disease begins when the LAST spot disappears, not when treatment begins.