High PH

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
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High PH

Postby seank156 » Fri 04 Jan, 2008 17:58

I have a pool business for about a year now and have about 85 pools different sizes. my ph has always been 7.8 or 8.0 and ive always kept the alk at 80-120. I use the taylors kit and use the acid demand test. but a few weeks ago i let the alk drop to 50 or 60 and my ph's were perfect. this past week my ph's are high.

I live in south florida and the past three days it has gotten down to the 30s. Does the cold temp have something to do with the ph's getting high. Thanks.

chem geek
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Postby chem geek » Fri 04 Jan, 2008 20:40

There is a pH variation with temperature, but it is relatively small. Going from 85F to 50F in water temperature would have the pH go from 7.5 to 7.7 if the TA were 100 ppm. However, there is always a tendency for the pH to rise due to carbon dioxide outgassing because pools are intentionally over-carbonated -- that's what TA most is (carbonates). The only way the pH would go down is if an acidic source of chlorine were used such as Trichlor or Dichlor. Bleach or chlorinating liquid or even Cal-Hypo are actually pH neutral when one accounts for chlorine usage which is acidic. Even an saltwater chlorine generator (SWG) is pH neutral when accounting for chlorine usage BUT the SWG produces hydrogen gas bubbles that aerate the water and cause more carbon dioxide outgassing and hence a strong tendency for pH to rise.

To reduce the effect of pH rising, one can lower the TA by following the procedure posted in this link.


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