Strange results in alkalinity

[urbanjaybird]

I just ran a test this morning of my pool water using tf100 kit.

Results
Fc - 6.5
Cc < .5
Ta - 90
Ph 7.5
Cya - 90

I wanted to lower my ta to about 70. Per the pool calculator I used 48 ounces of muriatic avid to lower my ph. This wasdone around 11:30 this morning.

I just tested my pool again and now have results below
Fc 8 (need to adjust SWG %)
Cc < .5
Ta - 110
Ph 7.3 (I've been running waterfall since 11:30 to aerate)
Cya (didn't retest)

I tested my ta again thinking I did something wrong, but got same results

Is there a period that would give me a false ta reading after adding the acid that I should have waited to test?

 

[jblizzle]

You should only have to wait about an hour.

Are you wiping the tip of the bottle between drops? Do they all look the same size and slightly hang on the tip of the bottle?
extended-test-kit-directions-t25081.html#p206395

 

[urbanjaybird]

I did do it for the second test that resulted in the 110 reading. Being that it was higher than originally thought I carefully double checked the test by meticulously following the extended testing steps.

 

[Richard320]

Is there any scale in that pool that you might be dissolving back into solution?

 

[urbanjaybird]

None that I had noticed. Only place I could think of scale would possibly be on rocks from waterfall. I hadn't run it in a week or so, and I hadn't looked at it up close prior to starting it up today. I'll retest in the morning and take it from there.

 

[duraleigh]

I wouldn't overthink that TA discrepancy too much. It is quite possible the first test had some testing error. The accuracy of the test is plus or minus 10 ppm. Assuming you get 100 or so again, just ignore the first test.