pH keep shooting up

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Eddles
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pH keep shooting up

Postby Eddles » Mon 18 Apr, 2022 05:27

Hi all,

I noticed that recently, the pH of my pool keep rising quite quickly, normally it takes forever to rise, but it seems to rise from 7.2 to 8.0 in the matter of one week. Only thing that has changed is that the pool cover has failed and is stuck open, would this cause the rise? I'm currently putting in 2kg of dry acid per week to counteract the rise. Everything else checks out fine, FC, CA, TA, CH all perfect. Thanks for advice in advance!


Teapot1
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Re: pH keep shooting up

Postby Teapot1 » Mon 18 Apr, 2022 07:43

FC, CA,TA,CH are all perfect according to?
The pool industry loves to sell and is very accomplished at doing so. Meanwhile with the help of Chemgeek and others we worked on the science to get to the real situation. If the pH rises rapidly you have too higher TA.
My TA is around 40 which means I have not had to add any pH minus in a few seasons, 1 litre of acid has lasted about 3 seasons from memory. What are your actual water test results as perfect does cut it because you wouldn't have a problem. We do new perfect, one that suits your pool and your pocket.
CYA level is also needed as it controls what goes on in the water.
I may not give you the answer you want to hear, but I will give an honest opinion of your situation as you decribe it.
Eddles
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Re: pH keep shooting up

Postby Eddles » Mon 18 Apr, 2022 11:52

Me and my Taylor FAS DPD test kit. To be precise, my TA is 130, not perfect but close. When I said CA, I meant CYA, apologies.
Teapot1
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Re: pH keep shooting up

Postby Teapot1 » Mon 18 Apr, 2022 13:16

It wasn't a criticism, it was a request for information. The industry publishes some guidelines but they are wrong in some cases which is why we ask.
TA of 130 will cause you pH rises. Reducing the TA to 60-80 will dramatically reduce the pH rise.
Cant help further without a full set of water test results.
I may not give you the answer you want to hear, but I will give an honest opinion of your situation as you decribe it.
Eddles
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My Pool: 66000 litre indoor swimming pool with UV and sand filtration, and 1200 litre hot tub.

Re: pH keep shooting up

Postby Eddles » Sun 05 Jun, 2022 12:56

Fair enough, but I almost always have a TA of 130, but the pH never shot up this fast in the past… will try to reduce the TA to 60.

What sort of “full set of water test results” would you be looking for, please? Thank you!
Teapot1
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Re: pH keep shooting up

Postby Teapot1 » Sun 05 Jun, 2022 16:07

If your CYA has been high, as it is an acid, its acts as pH buffer just as TA does but downwards so offsets the high TA. When you reduce the CYA you loose that buffer so the TA buffer takes over and allows the pH to rise easily at a TA of 130 but much less at a TA of 60 and less still at a TA of 40 like mine.
Just to be more informative/annoying, if the pH is anywhere up to 8.1 it really doesnt matter so long as the free chlorine to CYA ratio is maintained so if your pH is stable at 7.9 leave it there, saves trying to battle it down but be aware that any metals present in the water can come out of solution as the pH climbs to around 8.1, so always safer to have it a bit lower around 7.6.
Full test results are Free chlorine, total chlorine, pH, CYA, TA and calcium hardness.
I may not give you the answer you want to hear, but I will give an honest opinion of your situation as you decribe it.
Denniswiseman
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Re: pH keep shooting up

Postby Denniswiseman » Mon 06 Jun, 2022 02:28

To reduce high total alkalinity use this method
A type of Aerator
creativpools
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Re: pH keep shooting up

Postby creativpools » Wed 08 Mar, 2023 10:48

Yes, a failed pool cover that is stuck open can cause the pH of your pool to rise more quickly than usual. This is because when the pool cover is open, the water is exposed to more air and sunlight, which can increase the pH level of the water.

When carbon dioxide (CO2) in the air dissolves in your pool water, it forms carbonic acid (H2CO3), which can help to lower the pH of the water. However, when your pool is exposed to air, the carbon dioxide in the water is able to escape into the atmosphere, which can cause the pH to rise.

In addition, sunlight can also break down chlorine in the water, which can cause the pH to rise as well.

It's great that you are using dry acid to counteract the rise in pH, but it's important to keep an eye on the pH level and adjust your dosages as needed to keep it within the recommended range (7.2 to 7.8). You may also want to consider getting your pool cover fixed or replaced to help prevent the pH from rising too quickly in the future.
Teapot1
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Re: pH keep shooting up

Postby Teapot1 » Thu 09 Mar, 2023 11:31

It is unlikely that CO2 in the air will dissolve into the pool water. At 40ppm TA which is mainly carbonates bi or otherwise there is roughly 7 times more CO2 in the water than the air and according to Boyles law it will only ever off gas to try and reach equilibrium.
There really is no need to fight the pH to 7.2-7.4 when cyanuric acid is in the water as the most important factor is sufficient free chlorine to sanitise the water based on the CYA/free chlorine ratio. This is something the pool industry has got wrong but still teach incorrectly to students. If you pool water is more stable at 7.6-7.8 let it stay there. The only danger with pH above 7.8 is the potential for any metals in the water to drop out of suspension and stain.
I may not give you the answer you want to hear, but I will give an honest opinion of your situation as you decribe it.

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