To much Phosphor

I read that using Cu to get rid of phosphor. Hwo many Cu is needed?

Are you in dirt or hydro?
Either way you're making it overcomplicated and risking overdosing your plants on Copper.
Dirt: Flush, flush, flush.
Hydro: Drain reservoir. Refill with balanced nute solution.

man, if you start fucking around with trace elements you'll only end up with probs...fresh, quality potting soil (along with almost every back yard soil that has anything at all growing in it) already has all that is needed and introducing an element without knowing precisely what the problem is can poison the soil for years to come.

K.I.S.S.