Since you medicated the tank, you need to get the cupramine out with carbon and then add a viable marine bacteria culture to get the ammonia (nitrogen cycle) up and running again. The cupramine will damage the bacteria you had. It might recover, but, if its climbing already, it can shoot up real fast and cause blood poisoning. If did come to that, its not reversable 9 times out of 10.
Agree with Josh, feed caulerpa and nori too.

The dilemas with powder blues are no different than any other fish we get that is branded as hard. I've caught fish myself and brought them home and had the healthiest fish ever. Totally different than what we get from our fish stores. Thats why I like buying from Sam. Fresh caught and never starved for weeks until we get them. I can hardly wait till he starts into the fish line. His stuff is awesome and its a night and day difference by comparison!