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When your CYA is high and you are dumping in the baking soda to raise your TA, why doesn't the soda neutralize some of the CYA too? I guess I just don't understand why baking soda works with stomach acid, which is pretty powerful, but it doesn't work on this. Enlighten me please! ;)
In fact, soda ash does neutralize some of the Cyanuric Acid. The Cyanuric Acid is present in the water in several different forms, but the most common are as Cyanuric Acid (CYA) and as Cyanurate Ion (CYA-). When you add soda ash, some of the Cyanuric Acid gets converted to Cyanurate Ion [EDIT] I had that reversed when I first wrote it -- sorry about that [END-EDIT] and this is why CYA contributes to total alkalinity -- it is a pH buffer just like the carbonates (baking soda or bicarbonate) buffer system, but not as powerful since it's lower in quantity.
Remember that neutralizing an acid does not mean destroying it. CYA (and the carbonates such as carbonic acid) is a "weak" acid in that it does not completely dissociate and give up all of its hydrogen ion that would lower the pH. This is in contrast to "strong" acids such as Muriatic Acid, that pretty much completely dissociates into hydrogen ion and chloride ion. Nevertheless, when you neutralize the Muriatic Acid, you are still left with chloride ion so in a similar sense you don't "destroy" the acid when neutralizing it. Only the hydrogen ion portion of the acid gets neutralized -- the rest of the acid remains intact as an ion (a charged chemical species in water).
Richard
OR to put it another way it changes the form of the chemical from cyanuric acid to cyanurate ions but doesn't change the effect the cyanuric acid and cyanurate ions have on your chlorine.
I knew I could count on you guys. Now I wish I understood all I know about it!
Thanks
Very informative & useful Thread - Thanks!
~Hoffmans