Can't raise pH above 7.4

JB7181

Member
Jul 13, 2021
10
Illinois
Pool Size
19000
Surface
Vinyl
Chlorine
Liquid Chlorine
Pool has been setup a little over a week and I can't raise my pH above 7.4 no matter how much I aerate. My starting ALK was 350 and I have brought it down to 200 by aerating to 7.4 and dumping MA in it but when I do that the pH drops below 7.0. The only way to raise my pH above 7.4 is add pH up but that raises my ALK. Is my high ALK the reason my pH won't go above 7.4? Is there another way to lower my ALK or do I just keep aerating to 7.4 and then dump MA in and let it go below 7.0 or do I leave it alone for a while and let it naturally lower?

pH under 7.0
FC 9.5 shocked last night
CC 0
Alk 200
CH 200
CYA under 30. Can see the dot a little when cylinder is full
 

Texas Splash

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Jun 22, 2014
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How are you chlorinating your water? Tabs are acidic which can influence the pH. If you're using liquid chlorine or regular bleach, your pH "should" shoot right up there to 7.8 - 8.0 with little effort and a TA of about 200.

Right now though, getting the pH into the mid 7s is most important. Even if you can't get the TA down any further, don't worry about it. You don't want the pH below 7.0.
 

JB7181

Member
Jul 13, 2021
10
Illinois
Pool Size
19000
Surface
Vinyl
Chlorine
Liquid Chlorine
I have been aerating since yesterday and I tested the water again. Why can I not get the pH to rise above 7.4? I'm using liquid bleach not tabs. Only chemicals used since opening was Metal Free, bleach, chlorine stabilizer, and super shock from Great Escape.

pH 7.4
FC 4.2
CC 0
Alk 225
CH 200
CYA under 30
 

JoyfulNoise

TFP Expert
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May 23, 2015
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Tucson, AZ
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The process for lowering TA is to add enough acid to drop the pH to 7.0-7.2 then allow the pH to rise on its own to 7.8 or so. Then you remeasure pH and TA and recalculate the amount of acid needed to get down to 7.2 again. You repeat that process until the pH stabilizes. If your pH happens to stabilize at 7.4 with a high TA (I doubt that’s the case but you never know), then consider yourself blessed or lucky because that’s highly unusual. As long as having high TA doesn’t cause you any issues with calcium scaling, then your water is fine and there’s no need to drop your TA.

Typically water with over 120ppm TA will have an equilibrium pH (pHeq) of ~ 8.4. That means if you let the water sit there and add nothing to it, the pH will eventually rise to 8.4. How long that takes depends on the water temperature and aeration. Cold water does not outgas dissolved CO2 as quickly as warm water does. So the rate of rise can vary quite a bit.
 
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JB7181

Member
Jul 13, 2021
10
Illinois
Pool Size
19000
Surface
Vinyl
Chlorine
Liquid Chlorine
Should I have more of an arc or push it more under water.
The process for lowering TA is to add enough acid to drop the pH to 7.0-7.2 then allow the pH to rise on its own to 7.8 or so. Then you remeasure pH and TA and recalculate the amount of acid needed to get down to 7.2 again. You repeat that process until the pH stabilizes. If your pH happens to stabilize at 7.4 with a high TA (I doubt that’s the case but you never know), then consider yourself blessed or lucky because that’s highly unusual. As long as having high TA doesn’t cause you any issues with calcium scaling, then your water is fine and there’s no need to drop your TA.

Typically water with over 120ppm TA will have an equilibrium pH (pHeq) of ~ 8.4. That means if you let the water sit there and add nothing to it, the pH will eventually rise to 8.4. How long that takes depends on the water temperature and aeration. Cold water does not outgas dissolved CO2 as quickly as warm water does. So the rate of rise can vary quite a bit.
PXL_20210919_234931808.jpg
Is this good enough or should I put more of an arc on the water?
 

an1vrsy

Bronze Supporter
Jul 10, 2018
420
Las Vegas, NV
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
No one has asked, or I missed it, is there some reason why you want to raise your pH above 7.4?
 

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an1vrsy

Bronze Supporter
Jul 10, 2018
420
Las Vegas, NV
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Your pool surface is vinyl. PH is a key component to reduce scale but you’re vinyl. pH in the 7s is fine. When your pH gets to 7.8 add MA to lower it to 7.4. Then let it drift up on its own to 7.8. Then repeat…. Eventually your TA will come down.

What is your fill water pH and TA?
 

JB7181

Member
Jul 13, 2021
10
Illinois
Pool Size
19000
Surface
Vinyl
Chlorine
Liquid Chlorine
Your pool surface is vinyl. PH is a key component to reduce scale but you’re vinyl. pH in the 7s is fine. When your pH gets to 7.8 add MA to lower it to 7.4. Then let it drift up on its own to 7.8. Then repeat…. Eventually your TA will come down.

What is your fill water pH and TA?
pH 7.4
TA 475
 

an1vrsy

Bronze Supporter
Jul 10, 2018
420
Las Vegas, NV
Surface
Plaster
Chlorine
Salt Water Generator
SWG Type
Pentair Intellichlor IC-60
Are you having testing errors?
Post #1 TA 200
Post #5 TA 225
Post #10 TA 225
Post #12 TA 475

Your post title is can’t raise pH above 7.4 Let your pH sit at 7.4
 

JB7181

Member
Jul 13, 2021
10
Illinois
Pool Size
19000
Surface
Vinyl
Chlorine
Liquid Chlorine
Are you having testing errors?
Post #1 TA 200
Post #5 TA 225
Post #10 TA 225
Post #12 TA 475

Your post title is can’t raise pH above 7.4 Let your pH sit at 7.4
No, the 475 is the fill water out of the spigot.
 
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JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
18,583
Tucson, AZ
Pool Size
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I assume you are using your Taylor kit to measure pH, correct? And you’re adding the correct reagent (R-0004) to the water sample (44mL in the large comparator block)?
 

JB7181

Member
Jul 13, 2021
10
Illinois
Pool Size
19000
Surface
Vinyl
Chlorine
Liquid Chlorine
I assume you are using your Taylor kit to measure pH, correct? And you’re adding the correct reagent (R-0004) to the water sample (44mL in the large comparator block)?
Yes, we are using the Taylor K-2006C kit. Yes, we are using the R-0004 in the large comparator and this morning I went and borrowed my neighbors test kit and got the almost the same results. His said the alkalinity was 230 and pH was 7.4. I think at this point we will just close the pool with the winter kit and stop trying to lower the ALK. Will the alkalinity cause any issues when opening it next year? This is the process we have been following.
 

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JoyfulNoise

TFP Expert
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May 23, 2015
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Tucson, AZ
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Pentair Intellichlor IC-60
Yes, we are using the Taylor K-2006C kit. Yes, we are using the R-0004 in the large comparator and this morning I went and borrowed my neighbors test kit and got the almost the same results. His said the alkalinity was 230 and pH was 7.4. I think at this point we will just close the pool with the winter kit and stop trying to lower the ALK. Will the alkalinity cause any issues when opening it next year? This is the process we have been following.

The process you attached makes no sense as it not based on any testing and simply has the user blindly adding constant batches of chemicals. That’s not appropriate but typical of pool store methodologies which are almost always flawed & inaccurate.

Please read through TFP’s Pool School and consult the TFP Wiki for more detailed information. You can use this link that describes the process for adjusting TA -


You can certainly close the pool if you want and TFP teaches users how to do that as well. It’s best to wait until the pool water temp consistently reads below 60F to avoid algae growth during the variable Fall temperatures.
 
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