TA Testing Variations

[quincy915]

Leslie's titration TA test is always higher than my home, Leslie's Taylor Total Poolcare DPD Test Kit. This time I got a 60-70, they got 90! I got pH 7.6 (very happy), they got 7.8. These tests were only 12 hrs apart with no rain, water add, etc. Only bleach. Now, because I've been battling pH drift, I'm starting to wonder about my testing. Because a higher TA would explain the pH fluctuations, etc. I've even mastered continual swirl while adding drops. I've redone my TA and get same results. I make Leslie's redo, they get same result. It's got to be the titration.
I figured with the heavy rains last week my TA would drop. The color change from green is to pink or hot pink - I wouldn't call this color red ever. Any help would be appreciated.

 

[JVTrain]

TA will only drop when you add acid to the pool or replace a significant amount of water with lower TA water. The heavy rains would drive your pH upward if the pool was uncovered. Rain drops provide LOTS of aeration, increasing carbon dioxide outgassing, driving up pH. Even 4 inches of rain would only lower your TA from 70 to 66 ppm by dilution with 0 TA assumed in the rain.

The TA reagent can be biased high on a newer reagent bottle due to build up of static electricity on the tip, making the drops smaller, but that appears to be the opposite of your suspected problem. Extended Test Kit Directions

All that said, trust your testing more than Leslie's. Are your reagents fresh? I would suggest getting a more complete home test kit than Leslie's, such as a TF-100 or K-2006. Use one form of testing to make your decisions. Mixing pool store testing and your testing will only lead to confusion.

 

[Argosy]

The color change from green is to pink or hot pink - I wouldn't call this color red ever. Any help would be appreciated.

When they state on the kit instructions "untill the sample will turn red", they mean any shade of red color. As soon as you notice the change, that is your TA result. Sometimes I add couple more drops just to be sure. My sample turns just a little bit pinkish.

My Calcium Hardness test is even more confusing when changes color

 

[Agent99]

Basically, keep adding drops until no more color changes. This means that you will subtract the last drop to get your reading. Sometimes being out in the sun is better to gauge color changes...sometimes near a sunny window. Sometimes our eyes play tricks on us so ask someone else to try the test and see what they get.