I'm not a Chemist, but I think that soda will raise the pH even higher - you don't want that!
I have moved to an area that has a real high level of alkalinity in the water (it took 110 drops of "pH Down" per gallon - and two sessions - to get the pH down to 6.8. My first impression was "This could get expensive really fast!". Is that even possible - or am I doing something wrong? I don't know what the "starting" pH was because my kit only reads from pH-6 to pH-7.6 - anything outside that range just registers as "minimum" or "maximum". It took about 70 drops just to get the pH down off of the "maximum" reading. I am not familiar with this high of a pH reading - it seems more than "just a little" extreme to me. Is this normal?
If this is normal; and I'm just stuck in "Alkaline Hell", what are some other, economical, ways to deal with the problem? I'm paying about $5. for 1 and 1/4 ozs. of pH Down. Right off the top of my head, that's about $1. a gallon for water! Something ain't right! I'm thinking of getting some "Swimming Pool Acid", goggles and a rubber apron. Let's hear from somebody else out there who has a real high pH problem! In the mean time I'm using bottled water (not what I want for a permenent solution).
I'm concerned that the "weaker" acid in vinager or lemon juice might require so much volume that the "other ingredients" may become a problem. Would really like to hear from someone who has whipped the high pH problem.