most people tend to do 4 weeks with Cupramine @ .5ppm strength.
PraziPro - you want to do two dosings, 5-7 days apart. the first dose kills the adults, then it takes a few days for the eggs to hatch (not killed by the first dose). so the 2nd dose kills the new hatchlings. this is technically doing the same thing CoralsAddiction is saying with "5 day prazi treatment twice about 48 hrs apart"; just note that PraziPro loses its effectiveness after 3 days, so you are OK to do a water change around that 3 day mark.