I had a small amount of copper in my tank like three years ago. It was a trace amount cause it couldn't even be detected with a copper test kit. There was enough how ever to kill all my inverts. Recently I had to move my tank and I replaced all the sand. I am now seeing lots of worms coming out to feed. I also bought some of that poly fiber stuff that detects metals in your water. No copper. Can worms be present if there is copper in the tank? :spin2: