Ich tomonts can last up to 72 days (according to one study), but by transferring the fish away from the danger they cannot be reinfected by the free swimmers those tomonts release. However, it is absolutely imperative for the copper level to remain at full therapeutic for the entire time during this 14 day treatment period. You even transfer the fish from full therapeutic copper into another (non-medicated) QT at least 10 feet away. Reuse nothing from QT1 for QT2.