Pool math app giving different values to lower pH

[EndlessSummerAZ]

Using pool math and a TF Pro.

Test says pH is 8.2 and I want to lower to 7.4. In the pH section the app says to add 17oz to bring me to 7.4. When I look at effects of adding, it says 17oz will drop pH only 0.4 which would be down to 7.8. Those numbers are obviously giving two different values.

What am I missing here?

 

[mknauss]

Read the Note on the Effects of Adding page. Your change is outside the area of accuracy.

 

[EndlessSummerAZ]

Read the Note on the Effects of Adding page. Your change is outside the area of accuracy.

Range on the note says +\- 0.4 from 7.2 to 7.8. Even with a +\- 0.4 it would leave me at no change or only drop me to 7.6 from 8.2….right?

 

[mknauss]

The Effects is only for changes of 0.4 pH or less. With TA 80-120. And pH starting between 7.2 and 7.8.

 

[EndlessSummerAZ]

The Effects is only for changes of 0.4 pH or less. With TA 80-120. And pH starting between 7.2 and 7.8.

Good to know, pH starting values. Thank you!