A&H Washing Soda is chemically identical to the pool stores' pH raisers, like pH Up!--but far cheaper. Both are Soda Ash--Sodium Carbonate.

Without getting TOO technical, Borax raises pH and, while it appears to raise Alkalinity, it's only the change in pH that shows Alkalinity higher. However, Washing Soda will raise BOTH pH and Alkalinity levels.

You COULD use Borax and regular A&H Baking Soda (Sodium BIcarbonate) to get the same effect but Washing Soda does both and is cheaper lb for lb.

Chem_Geek can explain it to you better, but FC breaks down the CC. It takes about 7ppm of FC to eliminate 1ppm of CC (I THINK that's the ratio--Richard, correct me if I'm wrong). So you need to shock sufficiently to get rid of the CC.

BTW, it's the CC that irritates eyes, nasal passages, skin, and has that distinctive "chlorine smell". You actually get rid of the smell in your water by adding more chlorine! My pool is usually around 6-10 ppm and you ONLY smell chlorine when you get out of the water --as it has been neutralizing the impurities on your skin and there's a local bit of CC there as a result--and you smell like chlorine!