You can test your fill water. Did you fill your pool from a well or other source?
You will need to a metal sequesterant.
If your fill water is copper free, you can do a partial drain to lower the amount, and then use a metal sequesterant. But if the fill water is the source of the copper don't bother with that step.
Metal sequesterants can be found by doing a search on here, I don't totally understand the science of it... it deactivates the metals so they can't stain things, like blond hair and your pool surfaces. But it's a routine maintenance thing. Once you have copper in your pool, you will always have it and have to use the sequesterants.
Ionizers are nothing but trouble. I highly advise you lose it, really.