How do I maintain PH while raising TA?

[newtubuser413 1]

Tested my tub.  PH = 7.8, TA = 65, FC = 4.5, CH = 100.  According to Nitro's water maintenance, TA is low and CH is low-ish.  I will raise CH tomorrow (bought calcium chloride coming tomorrow).  I added two tablespoons of baking soda but I know it will raise PH as well as TA.  I'd imagine PH will be at least 8.0 next time I test.  For future reference, how do I ONLY raise TA without PH since my PH seems to be at a good level?  

[waterbear 143]

On 4/3/2021 at 2:18 PM, newtubuser413 said:

Tested my tub.  PH = 7.8, TA = 65, FC = 4.5, CH = 100.  According to Nitro's water maintenance, TA is low and CH is low-ish.  I will raise CH tomorrow (bought calcium chloride coming tomorrow).  I added two tablespoons of baking soda but I know it will raise PH as well as TA.  I'd imagine PH will be at least 8.0 next time I test.  For future reference, how do I ONLY raise TA without PH since my PH seems to be at a good level?  

Short answer, you can't. I would not have raised the TA. Nitro initially based some of his levels on pools and not spas and did not take into account the much higher aeration in spas that tends to cause pH to rise.

[newtubuser413 1]

Thanks.  I ended up lowering it again with sodium bisulfate after reading some more...looks like PH is really the number I need to pay attention to and TA is there to stabilize.  My PH now is at 7.4 and my TA is around 75.  Thanks for answering!