I do a large water change between each med. Depends on the bioload and the size of the QT, I may do water change every 2-5 days. My QT is uncycled, so I keep close eye on ammonia.
ParaGuard need to be dosed daily. I dose for 5-7 days.
ParaziPro one dose lasts 5-7 days. I change water on the 6th day, and add another dose.
Cuppramine need to be at full concentration of .5 for 2 full weeks. The instruction says to put half a dose and the other half 48 hours later. I like to add half a dose for 1 week, and if the fishes look ok, I add the other half of the dose and keep it their for 2 weeks. After water change, I make sure to up the dose back up.Then, you can observe the fish for another week or two. It depends on how they look like and whether they showed any sign of disease.