How much borax

[CalebM12]

I understand that borax can increase the ph without having much impact on TA.  If the ph is 7.2 and want to raise it to 7.6 how much borax per 100 gallons is recommended?

[waterbear]

If your pH is 7.2 I would not worry about raising it. It will rise on it's own from outgassing of CO2, particularly with a hot tub since the amount of aeration from the jets will outgas CO2 quickly. a pH of 7.2 is certainly in range for chlorine, bromine, and biguinide.

For reference purposes, dose at double the amount of pH increaser (sodium carbonate) requred for the pH increase. A good rule of thumb is to add half the required amount, wait a few hours, retest pH. Repeat, adding half of the remaining amount each time until you reach the correct pH. This way you 'creep up' on to the correct ph and don't overshoot. How much the pH increases depends on your current TA so there is no hard and fast rule.You must test.

Read this:

https://www.poolspaforum.com/forum/index.php?/topic/52522-some-truths-about-ph-and-ta/