TA not dropping

[EndlessSummerAZ]

Start up pool. PebbleTec recommended range is PH 7-7.4 and TA 80-100. Following this until the pb gets my water sample.

On Day 2 of testing myself with TF Pro. Yesterday my PH was 8.2. TA was 110. Added the recommended amount of muriatic acid. Checked PH later in the day and it had dropped to 7.4. Was in a rush so I couldn’t get to TA.

Today, PH is back again to 8.2 and TA is 110. Does it take awhile for TA to drop? Or is it simply because PH didn’t drop to 7 to 7.2? I would except some sort of drop even going to 7.4 for PH but I know nothing yet.

 

[HermanTX]

It does take a while for TA to drop. Also, in reading pH it is a color match but with TA testing using a 25ml sample, you multiply your drops by 10. So there is always a possible accuracy range of +/- 1 drop or 10ppm.
So for your pool volume, adding 1 cup of 31.45% MA, you could predict a drop of pH by 0.2 and TA drop of 2.7. That 2.7ppm decrease will not show up in your TA test because of the 10x multiplier.

This is why we suggest to monitor pH and continue to add MA to control that and TA will gradually decrease over time.

EDIT - suggest you use PoolMath app It has a section on Effects of Adding and you see the potential change.