Alkalinity drop from 90 to 50 overnight?

[mShark]

Yesterday I added MA to continue bring down my TA. I tested pH of 7.6 and TA of 100. I added 25 oz. MA. Today I tested to follow up on my SLAM and look at the TA and it was 50. Ran the test again because it change so quick making sure I counted the drops.

Can the total alkalinity change that fast? I cleaned my test lit with alcohol and tested again with the same result.

 

[JamesW]

Maybe sample size error?

 

[JamesW]

Can the total alkalinity change that fast?

No, the expected change is about 10 ppm.

 

[PoolStored]

Testing errors:
Sample size incorrect?
You need to add drops until the color does not change, then subtract the last drop.
R-0009 can get a static charge. Wipe the tip with wet paper towel before using to eliminate this issue.

My GUESS is that you had static when you got the 100.

Try it again:

Total Alkalinity

A drop-based test used to measure the alkalinity in water. Alkalinity helps serve as a … Read more…

www.troublefreepool.com

 

[sande005]

...Today I tested to follow up on my SLAM ....

If you were doing a SLAM, pH (and likely TA) will be invalid tests to run at high CL levels. Retest after the CL drops to 10 or below.