Dave,
I guess if those are your only choice then buy the smallest amount possible and don't use them again. However, I'd try and find some without the copper. I posted somewhere a while back about pucks at Sam's Club. Same brand, one pail (40# I believe) were plain, the other pail said 'multi-acting' or something like that but the ingredients said nothing about copper but it must have contained it. Also $10 more. Just be aware of the tricks in labelling.
Al