PH and TA Rise

[Shock11]

It seems my PH and TA will not stabilize and slowly rise every week. What could be causing this? I'll attach today's numbers.

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[Richard320]

1. "2 port fountains, bubbler in tanning deck"
2. High TA
3. Fill water probably high pH and TA

Aeration drives pH up. So does high TA. Try knocking the pH down to 7.2 whenever you add acid. That will lower the TA and should slow the pH rise as the TA gets down to the 70ish range.

 

[pooldv]

Here are some possible things impacting PH rise.

When was the pool finished?
It can take up to a year for plaster to fully cure and stop contributing to PH rise.

Are you running water falls, bubblers or other water features?
These all cause aeration which causes PH to rise.

What is the TA and PH of your fill water?

Lowering your TA to 60 or so will help to reduce PH rise. Here's how, Pool School - Lower Total Alkalinity

 

[Shock11]

Pool was finished in November. I don't really ever run the bubbler or fountains. I just added acid to lower ph to lower TA. I've done it a few times. Then I'll aerate to bring ph back up.


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[Texas Splash]

Even still, your TA seems to be returning to the 80-90 range. You could easily go down to about 60. Try allowing the TA to remain low in stages and that should help keep the pH from climbing so fast. Since your plaster was just re-done in Nov, it's probably still curing and driving-up pH on its own. That could take several months to slow down. Good to keep MA on-hand.

Oh, and remember ... your fill water (when used) may also increase TA which will in-turn increases pH.

PS - I like that spreadsheet you're using.

 

[Shock11]

I've got my fill water in an old post somewhere I'll try to find it.


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[Shock11]

Fill Water Test
Here are the results...



FC = 0

TC - 0

CH= 175

TA = 100

CL = 0

pH = 7.5


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[Texas Splash]

Those are fairly typical fill water TA/pH levels. No doubt the new plaster and slightly elevated TA are responsible for increasing pH a little faster that you might typically like. Consistent use of acid to lower TA and pH is certainly the way to go. As noted in Post #2, shoot for a pH target of about 7.2 which should bring the TA down with it. The let the pH rise on its own or aerate a bit if needed and repeat the acid/aeration cycle. Eventually the TA will get lower to the 50-60 range which is just fine for you.

 

[Shock11]

Got it. Thanks for all the help.


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[JoyfulNoise]

Also, once you get your TA lowered, switch to a pH target of NO LOWER than 7.6 and don't add acid until it is above 7.8. Many people make the mistake of thinking that pH has to be 7.4 or 7.2 or some fictional number based on the pH of human tears, blah, blah, blah. Water pH anywhere from 7.2 to 7.8 is completely comfortable and manageable. When one tries to artificially lower the pH below 7.6, it never stays there long enough to matter and they usually wind up consuming all of their TA and getting into a bad cycle of baking soda and muriatic acid additions. If you target a 7.6-7.8 pH zone, it will typically give you a decent interval between acid addition. Your incoming fill water will provide all the alkalinity you need. In fact, one of the best ways to cut down on the pH rise and frequent acid additions is to cover the pool to keep the evaporation low.

 

[Shock11]

Also, once you get your TA lowered, switch to a pH target of NO LOWER than 7.6 and don't add acid until it is above 7.8. Many people make the mistake of thinking that pH has to be 7.4 or 7.2 or some fictional number based on the pH of human tears, blah, blah, blah. Water pH anywhere from 7.2 to 7.8 is completely comfortable and manageable. When one tries to artificially lower the pH below 7.6, it never stays there long enough to matter and they usually wind up consuming all of their TA and getting into a bad cycle of baking soda and muriatic acid additions. If you target a 7.6-7.8 pH zone, it will typically give you a decent interval between acid addition. Your incoming fill water will provide all the alkalinity you need. In fact, one of the best ways to cut down on the pH rise and frequent acid additions is to cover the pool to keep the evaporation low.

I try to keep it at 7.8. The kids have been swimming and haven't complained a bit except they say they can taste the salt.

 

[Frankhugus]

Even still, your TA seems to be returning to the 80-90 range. You could easily go down to about 60. Try allowing the TA to remain low in stages and that should help keep the pH from climbing so fast. Since your plaster was just re-done in Nov, it's probably still curing and driving-up pH on its own. That could take several months to slow down. Good to keep MA on-hand.

Oh, and remember ... your fill water (when used) may also increase TA which will in-turn increases pH.

PS - I like that spreadsheet you're using.

Where is that spreadsheet from? Homemade? Pool Math one of the tabs? Nice!

 

[txnole]

Forum butchered the link url. Should be https://drive.google.com/uc?export=download&id=0B3uld5Tf0bM4Z1RfVUtROS1rRHM