High pH, alkalinity and hard water

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

High pH, alkalinity and hard water

Postby Nancy in Illinois » Sun 24 Feb, 2008 16:29

I have a 30 thousand indoor gallon pool. I have hard water, high Ph, high Alkalinity. I have been adding acid on & off since December, and can not balance.

The Ph comes down for one day and then goes back up. I was able to bring Alk down one time, but it went back up that evening?

I have not touched the pool in a week - Right now my Ph reads error and my Alk is 287. Pool burns eyes if you swim underwater to long and makes skin itchy.

How do I correct this?


High TA and high pH

Postby Poolz » Sun 24 Feb, 2008 16:37

Firstly you need to reduce the alkalinity. High alkalinity will keep pushing the pH up in a short time. Read the first sticky post in this forum about reducing high TA.

By the time the alkalinity is normal, the pH will be stable and then we can do something about the hardness.
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Postby muss08 » Sat 08 Mar, 2008 17:13

If you have high calcium levels in your pool then this must be taken care of first. The only way to reduce calcium is through dilution. Drain 1/3-2/3 of your pool and refill. Then retest and go from there. If both pH and TA are still high add muriatic acid. The acid will lower both the pH and TA but only worry about TA for the moment. Once that falls into normal parameters balance the pH. Burning eyes can be caused by low pH or chloramines. Since your pH is high you need to run a combined chlorine test. If this is above .5 ppm then you need to shock the pool. This will kill the chloramines.
chem geek
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Postby chem geek » Sat 08 Mar, 2008 18:53

The ONLY way to reduce TA is through a combination of acid addition AND aeration of the water. Of course, there is always some outgassing of carbon dioxide if the pool is uncovered, but intentional aeration will speed up the process as described here. The outgassing goes faster with more aeration and at lower pH which is why the procedure has you first lower the pH and then aerate and add acid to keep the pH low.

Pools are intentionally over-carbonated (to provide a pH buffer and to supply carbonates to saturate the water with calcium carbonate to protect plaster from dissolving), similar to a carbonated beverage. Just as stirring up a beverage or blowing bubbles in it drives off the carbon dioxide faster and makes the beverage go flat (and also raises its pH), the same is true for pools.


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