pH is very high after adding baking soda

[Horanis]

Hello all,
My chemistry prior to adding baking soda were:
pH: 7.1-7.2.
TA: 40.
CYA: 40
FC: 6.

Two weeks ago I added soda ash to increase pH to 7.4 and it worked but today pH came back to 7.1-7.2. I thought this was likely due to low TA. I decided to increase TA to 50-60. I used Pool Math and recommended to added 2 lbs, 3 oz but I added only 2 lbs baking soda and waited 6 hours. I just retested pH and it is above 8 and TA is 50. Water is clear.
I thought baking soda does not affect pH much. So what happened here? Should I add muriatic acid or wait a day and retest again?

P.S. Did not SLAM recently.

Thank you.

 

[mknauss]

The data does not add up. I would test again tomorrow.

Are you using trichlor to chlorinate?

 

[Horanis]

The data does not add up. I would test again tomorrow.

Are you using trichlor to chlorinate?

I will retest tomorrow. I only use liquid chlorine.

 

[Horanis]

I retested this morning and pH was still 8 and TA is still 50. I added muriatic acid and it is now 7.6 and TA stayed at 50. I will keep it at 7.6 for now. I am still not sure how baking soda made pH jump that much.

 

[YippeeSkippy]

Got any fancy water features running? Fountains, spillovers?? Things like that??

 

[YippeeSkippy]

For reference-

 

[Horanis]

Got any fancy water features running? Fountains, spillovers?? Things like that??

Nope