Vtatt;

It's hard to dispose of chlorine tabs legally, except via your pool. If you didn't have problems with copper staining or green hair last year, I'd recommend that you DO use the tabs up, but VERY carefully, also using of bleach (added to the pool) as a chlorine source, to keep the copper levels down. Also, put the tabs in the skimmer, not in a floater. That way some of the copper will end up staining the dirt in the filter, and then being washed out.

Because of the copper in the backwash, be careful where the backwash goes. You do NOT want it to go in a stream, where it could kill things.

Also, in addition to using a mix of bleach (to shock, added to the pool, not the skimmer!), use borax to push your pH up toward 7.8. This will also help remove the copper on the filter.

Also a CAUTION: your low pH helps keep copper soluble. You may have a LOT of copper in the water, now. When you raise the pH, the copper will tend to come out, causing stains. If you can get a copper test done, do so. If you've got copper in the water, do NOT raise the pH yet, at least not beyond 7.2, and do NOT start using the tabs yet. Instead, get a liquid stain / scale product, and dose your pool with it. It will temporarily keep the copper soluble, but then will break down slowly. If you run your filter 24/7 and gradually raise the pH, the copper will tend (no guarantees) to come out on the filter.

Alternatively, you can buy the CuLator product:
1 ppm Culator, direct from Amazon
1.5 ppm Culator, sold by Amazon, shipped from Periodic
4 ppm Culator, sold by Amazon, shipped from Periodic
We *think* these work but haven't absolutely established that yet. The company claims the CuLator will remove the copper, even when it's sequested by a liquid stain scale product. If you get the CuLater, you probably want to use it with this:
Poolmaster 16242 Poolmaster Skimmer Basket Liner
to keep it from being ruined by pool goo. (Put the CuLator UNDER the skimmer sox!)

Finally, if you DO get the CuLator, do NOT put chlorine tabs in the skimmer with it -- we're not sure what would happen. Instead, put them in another skimmer (if you have two) or in a floater.