I had better results doing the opposite, water changes first then Cuprisorb and carbon.
2-3 big water changes gets it 0.3- and then let the Cuprisorb and carbon take over.
Following up on this post. Just today I tested a 90-gal DT that had been treated with CopperSafe for 21-days at 2.0. It's had four(4) 25% water changes in three weeks, running 200 ml of Cuprisorb in the fine mesh bag hanging inside the tank itself, and three(3) lbs. of carbon at 1-lb each week. After 3-weeks copper is undetectable (0.0) based on Hanna and Exact iDip testing.
Thanks for the update man. Very much appreciated. Was thinking about stopping at 30 days but saw a white spot on my blue tang. Once I've done the full time I'm considering dropping a few black mollies in and seeing if they get ich at all.
Today's copper level is 2.58 with no dosing since Sunday.
Think I'll give the, water change first and then media reduction, a try.