High TA, pH=7.4....using Co2

[Pmchick]

Hello, everyone,
My TA went from the low 100's (100-107ppm) to 194ppm this morning !? I test the TA everyday, so, this was a surprise. I re-tested it in different areas (pump runs 24/7), and still came up with results greater than 120ppm.
The pH was a 7.4, FC: 3.06, TC: 3.23, CH: 300.
This is a plaster pool, and the pH control is Co2. I understand that Co2 has a tendency to increase the TA, but, if in fact this is a true TA reading, how dud it suddey shoot up that high?!
My test kit is the LaMotte ColorQ-pro 7. The vials are brand new as are the reagents. The light chamber is also clean.
This just seems very bizarre, could it be my test kit? This has never occured.


Thank you

 

[JasonLion]

I am assuming that your CO2 system maintains a constant PH, so there shouldn't have been any large PH changes recently. The TA will go up if your raise the PH.

If your pump is running all the time and you circulation pattern is at all good, you shouldn't be seeing any significant variation in the TA level from place to place on the same day without adding any chemicals between tests. What you said kind of implies that you measured various TA levels over a range that might be as large as 194 to something over 120? If the ColorQ is working correctly, all of your measurements should have been within about 10 or 15 of each other, or closer. If you are seeing wider variations than that, something is up with either the ColorQ or your testing technique. One way to look into this further is to test the exact same water sample a couple of times and verify that you are getting consistent readings.