Help with unexplained pH rise.

BWLutz

Member
May 1, 2021
5
Fresno, CA
Long time listener, first time caller.

I re-finished my 13,000 gal pool in November with a Wet Edge aggregate finish. Six months later the acid demand seems to be through the roof. I'm using 60oz a week to maintain the alkalinity and pH. Over the last few days I've done a series of test (Taylor k-2005) to try and figure out what is going on.

April 30th 2pm
FC - 5
pH - off the charts high. 8.4?
TA - 90
CYA - 35
Temp - 75F
CSI - .89

Added 64oz of 14.5% MA

April 30th 4:40pm
pH - 7.5
TA - 70
CSI - -.12

This is pretty much the change I was expecting with the MA treatment.

May 1 8:50AM
FC - 5
pH - 7.6
CSI - -.02

Not losing any CL overnight and a reasonable pH rise. At 930am my pool pump cycle starts up and at 10AM my stennar pump adds my daily dose of Kemtek chlorinating liquid (10%) approximately 33oz.

May 1 1230pm
FC - 8
pH - 8.0
TA - 90
CSI - .48

I'm maybe adding a bit too much CL but as the days get longer and hotter I will shortly need that much. But why is the pH spiking? I didn't think liquid CL affected pH. I know it can cause an increase but then readjust as it is consumed. I dont think it's aeration as my TA is rising as well. Could there be something with the relative new finish? Is my CL tank contaminated? Any ideas would be greatly appreciated.

I'll post the CL, pH, and TA numbers at the end of the day but I expect it will 5, 8.0, 90.

Thanks!
 

BWLutz

Member
May 1, 2021
5
Fresno, CA
I previously read all those. Is an increase of .4 pH and 20ppm TA in a 4 hour period expected? Seems like something else is going on.
 

duraleigh

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Apr 1, 2007
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That is not at all normal or, frankly, attainable, I don't think.

That sounds like a bad testing error. Are you using the phenol Red pH test from the K-2005 kit?
 

BWLutz

Member
May 1, 2021
5
Fresno, CA
Tested this morning at 7.6 now after running my stennar pump for an hour, adding 30oz of 10% liquid CL my pH is 8.0.
 

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BWLutz

Member
May 1, 2021
5
Fresno, CA
That is not at all normal or, frankly, attainable, I don't think.

That sounds like a bad testing error. Are you using the phenol Red pH test from the K-2005 kit?
Yes. It's a replacement bottle. Pretty sure I'm doing the test correctly.
 

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