BBB method--from the WalMart guy!

[chem geek]

This effect of metals on the rate of degradation is true and described here where there is a nice table of half-life of chlorine at various concentrations and temperatures near the bottom of the page. Roughly speaking, the product degrades 4 times faster with a doubling of concentration and degrades about twice as fast with a 10F rise in temperature.

Most manufacturers of chlorinating liquid, including Odyssey and Hasa, make a good product as far as I can tell from many different reports on multiple pool forums. I've tested the strength of my chlorinating liquid both via direct dilution and via the effect on the pool of known volume and they are always near the correct strength -- in the range of 12-13% where the claim is 12.5%. Once I got something that might have been 11.5%, but that was the worst I had.

Bleach degrades much more slowly because of its lower concentration, but I wouldn't shy away from chlorinating liquid. Just try it out and see if it behaves as expected.

Richard