[teriyakithunder]

i think copper kills the ich which is the parasite itself but it takes time. when ich reproduces it makes a cyst which hatch and new swarms of parasites go to find their host. the cyst can take anywhere from 3-28 days to hatch. then the process starts over. thats why most people put their fish in qt and kill the parasites there while at the same time letting all the cyst hatch and letting the parasites starve themselves to death from not being able to find a host to feed off of. also copper is toxic to fish over a long period of time.