What is going on?

[CarlD]

Washing Soda is chemically the same as pH Up! (and, yes, it does raise both pH and T/A)

Baking Soda is chemically the same as Total Alkalinity Increaser (guess what IT does!)

Borax is Borax. It just raises pH, not T/A.

Now, here's the rub: When you raise pH your MEASURED T/A rises, and when you lower pH, it falls. pH and T/A are related and connected.

The ONLY way to raise pH without raising T/A is by aeration--aerating your pool water with waterfalls, fountains, gangs of wild 12 year olds (Wait--wild and 12 year olds is redundant), etc.

But when you use Washing Soda or Baking soda, the T/A rises MORE than the variation caused by the change in pH, which is why we say they increase T/A.

Hope this helps.

[Watermom]

Carl has given you good information, like usual. To add to that, you're actually ok with alk at 80 and ph of 7.2 right where they are, but you don't really want them any lower. Also, I don't think you have CC of 15. More likely FC or TC of 15.

[chem geek]

Baking Soda raises TA. It can also raise the pH a little bit, but that depends somewhat on how you add the baking soda. If you add it too quickly, such that you see some bubbling on the surface, then you can end up outgassing carbon dioxide which raises the pH. If you instead add it slowly over a return flow with the pump running or you distribute it around the pool more evenly, then the pH won't rise as much. This effect is far more noticeable in a spa than in a pool, however.