Raising Ph Chemically

[dlleno]

After reading the stickies, I'm still not quite clear on the topic of raising pH chemically and the associated effect on TA. I get that any chemical method of raising pH will also raise TA, but what is the practical impact of adding sodium carbonate vs bicarbonate vs borax?

and along with this -- 20 mule team borax will raise pH but also add borates, meaning one should keep track of total borates, right?

[chem geek]

Aerating the water increases carbon dioxide outgassing and that raises the pH with no change in TA because you are essentially removing carbonic acid from the water.

Raising the pH using borax raises both pH and TA because adding any chemical base to the water will do that and as you point out it increases borates as well. If you were to add a lot of borax then yes you should probably keep track of how much you add, but usually you shouldn't need to add much base to a spa since it generally won't drop in pH very much over time and you can usually balance this by having the TA be higher.

Raising the pH using sodium carbonate raises both pH and TA, but raises the TA about twice as much as borax because you are adding carbonate. In fact, sodium carbonate is identical to adding sodium bicarbonate (raises TA) and sodium hydroxide (a pure base).

What method of disinfection are you using that has the pH drop over time having you need to add a base to raise it? Have you tried adjusting the TA higher to see if that helps?

[dlleno]

Oh I'm using bromine... But no real issue with low pH I raise ta towards the end of the water s life and I'm running 120 ppm ta now. I just wanted to understand the borax vs soda impact especially when borates are part of the pH plan.