Residual Effects of Copper ?

[DiverDude]

My tank has been suffering lately from Ich and/or something worse. My Flame Angel died first and then my damsel got what I believe is simple Ich but he's not eating much (if anything) and his behaviour has changed considerably. the tank suddenly has a lot of algae.

As part of the "how am I going to cure this Ich" process, I pulled out a bottle of copper treatment that I received with the tank. I noticed that this bottle was 3/4 empty. the person who owned the tank previously only had the one tank so I'm beginning to think that they did copper treatments in the tank with the LR !

So....everything was fine for a couple of months and then all this a little over a week ago. Could I be experiencing some kind of residual effect from copper leaching out of the LR ?

Maybe I'm trying too hard to find a cause for something that 'just happens' but I'd like to nail this down so I can learn from it and if it's possibly copper contamination, what I can do to help get rid of it.