Sorry I never followed up on this. It took me a few days to collect the data, and I just never got back here.

Sams's Club is selling the "Pool Brand" brand of pool chemicals through out much (maybe, all?) of the USA. There are 3 products in this like that are a GOOD deal.
1. The 50# bucket dichlor powder is often being sold BELOW wholesale (at least, below the wholesale prices that apply outside of Florida and California). Here, it's about $2/llb
2. The bagged shock (12 or 24) is pure dichlor and is HARD to find. It's also at a good price.
3. The 40# bucket of trichlor is also pure, and an EXCELLENT price.

If copper is present, I'm pretty sure it MUST be a listed ingredient on the container.

They also have 2 gallons of 40% linear quat algacide for under $30, I believe. Do NOT use this during swim season. But if you've got a sludged pool, it may be worth trying as a first cleanup step.