Your tank will likely never recover from this med. What happen to copper is that it bind to the sand and rock. High pH is OK but at time of low pH like at night or when you have a little problem, the pH drop and the copper will come out of the rock and back into solution. These events just not enough to kill your invertebrates out right but will keep them from being healthy.
I am sorry that you will likely have to discard your sand. If you want to reuse your rock you may have to acid treat them. Use copper binder will help somewhat.
Back in the 1990's one of my tank got semi crash when one of my pump housing cracked. It was an old style Rio pump. As soon as I see the animal in distress, I found the problem right away. I did tons of water change. I lived on the water so I just pump the water from Corpus Christi Bay and change water. The shrimps, and tons of worms died. LPS, and clams was semi Ok, SPS bleached but great majority lived. My tank was never the same after that. I had repeated algae outbreak, coral does not grow well. Fish OK and fat but coral and invertebrates never did well after this event. I broke down the tank after about 18 months, discarded everything and start over. Moving the corals to the new tank, they recovered and did well.