For the filter, I use a hang-on style. The filter without carbon has been placed in the sump of the DT for many months and will be taken out when setting up the QT. Although I may be looking into changing this up, when using copper, the ammonia will rise and I don't like performing water changes every day or every other day and might need more filtration. We can use Prime to help eliminate the ammonia, but not for the duration of the copper treatment.
After running a QT for a fish who had a disease and using copper, the tank will need to be drained and cleaned. For me, even the PVC plumbing pipes used for fish to hid or get-away, I get rid of instead of cleaning. The copper will settle into just about everything and when re-used, copper will still be present. Even the 5-gallon buckets I use that house's copper can be clean or placed in the trash.
For example new fish goes into the QT. after about 5 days of eating good, copper treatments start...over 4 days to get the desired copper level. After 21-30 (more like 30), slowly remove copper from the tank to almost 0 ppm. During the copper treatment, we mix up the food with GC/focus. After the copper treatment, use GC up to 2 times. Within a week and the fish is healthy, onto the DT. The QT is shut down. that is my process.
Just my two-cents worth...hope I helped.