Well this has never happened to us before in the 10 years we have been doing BBB. 
We have really low TA for the first time ever.
We have historically had really high TA, like 170-190 high. and every year we do the painful dance after opening to bring Alkalinity down to 90 so that we can add borates. This year our alkalinity was either 140 or 160 at opening. But my husband no longer has his Android phone and is now Apple like me, so we are using the Pool Math app for the first time this year. Oddly Pool Math has been having us add a lot higher amounts of chemicals than the other app we had used all these years. (The previous app is not available for iPhones)
We got our borates to 50 and our alkalinity was at 70/80 so I was happy, but when our pH swung up to 8.0 a few days ago the Pool Math calculator had us add over a gallon of 29.5% Muriatic Acid to bring it down to 7.6. ? Or so we thought. That’s what we entered for a target. My husband thought that was too much based on his past 10 years of experience, but thats what the calculator said so we did it. Well it brought the pH down to 6.8 and it also lowered our alkalinity to 40! Yikes
Now Pool Math is recommending 18lbs baking soda just to raise it to 70. So off he goes to Wallyville to buy that while shaking his head. We have never used baking soda once in 10 years. We have had it great only being BB method. LOL
Questions:
1) how do we add the baking soda? Broadcast over the deep end and let it dissolve slowly? Place it in the skimmer?
2) What’s up with Pool Math? It’s costing us more money with more product and that’s unusual. I have set our pool volume accurately. An example of our numbers when it had us add that gallon of acid:
FC 11.5
CYA 55
pH 8.0
TA 70/80
Borates 50
CH idk - historically comically high so we always ignored it
It recommended 1 gallon of 29.5% acid to reach target pH of 7.6. Was that accurate? Adding that tanked it down to 6.8.
We have really low TA for the first time ever. We have historically had really high TA, like 170-190 high. and every year we do the painful dance after opening to bring Alkalinity down to 90 so that we can add borates. This year our alkalinity was either 140 or 160 at opening. But my husband no longer has his Android phone and is now Apple like me, so we are using the Pool Math app for the first time this year. Oddly Pool Math has been having us add a lot higher amounts of chemicals than the other app we had used all these years. (The previous app is not available for iPhones)
We got our borates to 50 and our alkalinity was at 70/80 so I was happy, but when our pH swung up to 8.0 a few days ago the Pool Math calculator had us add over a gallon of 29.5% Muriatic Acid to bring it down to 7.6. ? Or so we thought. That’s what we entered for a target. My husband thought that was too much based on his past 10 years of experience, but thats what the calculator said so we did it. Well it brought the pH down to 6.8 and it also lowered our alkalinity to 40! Yikes
Now Pool Math is recommending 18lbs baking soda just to raise it to 70. So off he goes to Wallyville to buy that while shaking his head. We have never used baking soda once in 10 years. We have had it great only being BB method. LOL
Questions:
1) how do we add the baking soda? Broadcast over the deep end and let it dissolve slowly? Place it in the skimmer?
2) What’s up with Pool Math? It’s costing us more money with more product and that’s unusual. I have set our pool volume accurately. An example of our numbers when it had us add that gallon of acid:
FC 11.5
CYA 55
pH 8.0
TA 70/80
Borates 50
CH idk - historically comically high so we always ignored it
It recommended 1 gallon of 29.5% acid to reach target pH of 7.6. Was that accurate? Adding that tanked it down to 6.8.
Thanks for your help you guys.
- there are glitches in technology sometimes so bringing it up when there’s a problem is the right thing to do. 
is always helpful 