to answer your question about your display tank ? no it wont contaminate it,,i have a 125 fish only tank and i keep a very low level of copper in the tank at all times, well once its in it will always be there, but so many people dont recomend copper, my answer to that is VERY LOW LEVEL in a FISH ONLY TANK will not hurt the fish at all, 99 % of all fish suppliers keep copper in their tanks with the fish for sale in them so that they never get ich..... thats why if youll notice, all the tanks with fish in them dont have live corals,live rock or anything for that matter, just fake ornaments for decor,,,but anyway, thats what i do and have never had a problem,,just remember i said fish only for copper..good luck.