Hi, I'm a noob here at TFP with a basic question that the Web doesn't seem to answer.
I have an in-ground plaster pool/spa/waterfall with SWG, built 8 years ago. I keep up with the chemistry myself, and it's been very low maintenance (I run it year round). Recently bought a "real" chemical test kit (Taylor) and I'm enjoying the fine tuning and learning lots on this site.
My question: If the salt merely provides chlorine from a different source, and chlorine is consumed by organics and sunlight (hence CYA is needed), then why don't I have to constantly add salt to my pool to replace the "consumed" chlorine? I do add a little during the season, but so little that I don't keep track (maybe just to replace backwash and splashout?). However, I DO have to add muriatic acid REGULARLY. I'm always told, "new plaster pools will require a lot of acid," but it's 8 years old now. And many pool sites note that SWG pools "mysteriously" will have pH creep up and require routine addition of acid - but don't say why. I found only ONE site on the internet that claims the ACID is actually what's being consumed - i.e., instead of adding chlorine manually (solution or tabs), with a SWG you're adding acid manually. This site even had some chemical equations purporting to show how this works (as the salt's chlorine is used, sodium hydroxide is formed, and the HCl busts that up to give you NaCl and water again, or something like that). It made sense to me, but I'm just surprised there's so little talk about this, given the debates and misconceptions about SWG versus other methods. I just have a hard time believing in a "perpetual motion machine." Any thoughts are appreciated!