You “beg to differ”? Please stop with the misinformation. Clorox bleach is most certainly registered by the EPA as a disinfectant for swimming pool disinfection as well as for hot tubs and spas. It has EPA registration number 5813-50 or 5813-100 and is listed for “Swimming pool water , Swimming pool water (wading pool) , Hot tubs (outdoor) (water treatment) , Spas (outdoor) (water treatment)”:
http://www.pesticideinfo.org/Detail_Pro ... _NR=005813 (older 6.00% strength)
http://www.pesticideinfo.org/Detail_Pro ... _NR=005813 (newer 8.25% strength)
The service bulletin from Clorox explicitly lists uses “FOR SWIMMING POOL DISINFECTION” and “FOR SPAS, HOT TUBS AND IMMERSION TANKS, ETC.”:
http://www.clorox.com/pdf/5813-100_serv ... letins.pdf
The actual Clorox bleach label itself lists the % Available Chlorine as well as the EPA Registration Number.
It is true that you have to know what you are doing when using a hypochlorite source of chlorine such as bleach in a spa. You should not use it in a spa without having Cyanuric Acid (CYA) in the water first. An easy way to do this is to use Dichlor first to build up the CYA level to around 30-40 ppm CYA since for every 10 ppm Free Chlorine (FC) added by Dichlor, it also increases CYA by 9 ppm. Also, one needs to have the TA lower at around 50 ppm and should use 50 ppm borates (easily added using boric acid) for pH buffering. When you talk about the pH of bleach, for Clorox bleach it is around 12, not 13:
http://www.thecloroxcompany.com/downloa ... h0809_.pdf (11.9 for the older 6.00% bleach)
http://www.thecloroxcompany.com/downloa ... 092012.pdf (12 for the newer 8.25% bleach)
However, the usage/consumption is an acidic process so the net effect when using Clorox bleach is closer to pH neutral. One keeps the TA lower to less carbon dioxide outgassing that causes the pH of the water to rise, especially with aeration.
When used properly (i.e. with CYA in the water), the bleach does not get used up any faster than any other source of chlorine and requires no more frequent additions than any other source of chlorine.