Cheapest source for muriatic acid?

[chem geek]

(Maybe chem_geek can instruct us on how to make it from common household supplies )

Sorry, but HCl is typically produced from electrolysis of a salt solution, similar to what your SWCG salt cell does except it's done in a much more concentrated salt solution that is much more acidic. It produces chlorine gas and hydrogen gas that combine in a hot reaction to from HCl gas (an SWCG salt cell produces chlorine gas that gets dissolved in the water and should not outgas much because the pH is higher and the salt and chlorine concentrations are lower). Both chlorine gas and HCl gas are very, very toxic and destructive. Not something for the home-brew chemist to do!

If you find yourself adding lots of muriatic acid because you have a large pH rise, you might consider significantly lowering your TA level to at least 80 if not lower (but not lower than 50). This has helped many people reduce their pH rise. You could also use a pool cover. If you are using an SWCG system, then Evan (waterbear) found that adding 50 ppm of borates (Borax) to your pool does in fact significantly lower chlorine usage and lowering the SWCG output reduces the pH rise and the amount of acid you need to add. See this thread for more info.

Richard