What is in your main tank? You can not treat with medications or hypo if you have LR, LS or inverts.
I would do a water change, and, if you have carbon filtration, begin that to pull out the copper. If you use copper in your main tank fo 3 weeks, you will crash the system, which might happen anyway.
Begin hyposalinity and over the next 2 days, in slow increments, reduce your salinity to 1.009. Maintain this for 3 weeks following all signs of ick disappearing from your fish. Continue regular water changes paying special attention to Ph, as hyposaline water tends to get too low in Ph. Maintain your usual water temperature.