Furan 2 was a good choice. Copper, however, was not. Not only has it complicated your whole planting system, but it is also very dangerous in the sense that it has a highly variable toxicity (to both pathogens and fish). If you're treating a bacterial infection, I'd ditch the copper now and just let the nitrofurazone and furazolidone do their job-- this will also be much less taxing on the fishes' kidneys. I'd suggest removing the copper right away, which you can only do through chelating agents (almost always EDTA) and/or water changes. Since it's hard to get a hold of EDTA (ethylenediaminetetraacetic acid), you'd be better off doing a series of large water changes. The volume will depend on how comfortable you are with such water changes; reallistically, you could do a 100% water change, replace all the water with water of identical parameters, and only cause minimal stress by temporarily rehousing the fish. If you'd rather avoid that, a series of 3 75% water changes or 8(ish) 50% water changes will effectively remove the copper from the system in enough quantity to negate any threat to the plants.
