pH high and TA low-question

[sdunk]

I have been following the BBB method for 1 year now (I guess it's my anniversary) but I have never needed to adjust my TA, it has always been in the acceptable range for a manually chlorinated pool. We have had more than 3 inches of rain here in the last 24 hours so I knew that the water was going to need attention. Here are my numbers:
FC-0 (gotta adjust the pH first)
CC-0
CH-75
TA-80
CYA-20
pH-8

Pool math it telling me to add 19 ounces of muriatic acid and 83 ounces (volume) of baking soda. Do I do both? Won't adding the acid change the amount of baking soda or vise versa? I have never needed to add baking soda before but I have it here on hand for a time such as this. Are the pool math calculations taking all that into account?

Thanks ahead of time for your help!

 

[tim5055]

Your TA is really not low. For a vinyl pool we give a range of TA 50-90. I keep mine at 60 and find my pH much more stable

Pool School - Recommended Levels

Add the acid and skip the baking soda for now. Watch how your pH reacts moving forward.

 

[Lawtyger]

I ran into a similar issue for the first time months ago where for the first time ever my TA seemed lower than it had been since the pool opened in March 2016 and it was the first time I seemed I needed to adjust my TA. I did just to try to keep in more in the middle of the range but it kept dropping back down to 60. Ultimately my TA settled in at 60 and has remained consistent at that lower end of the range. The advice I was given here was that all pools are a little different and to treat your pool accordingly as long as the TA number was in range which it was.

Your TA seems to be in range so it may just settle in at the Lower end of acceptable.

 

[Donldson]

It is a surprise for most people how low they need to let their TA drop to stabilize their pH after they switch their pool to a mostly liquid chlorine diet. Keeping TA higher (100-120) makes sense when using trichlor to chlorinate because trichlor is very acidic. Liquid chlorine has a very high pH however (though it is mostly pH neutral in use) so allowing the TA to drop much lower than we are trained to consider safe is actually quite prudent.