How do I keep my pH stable?

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
Oregonmommy
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My Pool: 15' round 42 " deep abouve ground pool
Location: Oregon

How do I keep my pH stable?

Postby Oregonmommy » Sat 25 Jul, 2009 21:30

Chlor. 2-3
TA- 80
Ph- 6.8 -7.2 closer to 7.2
How do I keep my pH stable. I added some pH plus and got it at 7.4 but after a few days it dropped back down even with everything else staying in normal range.


Denali
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How do I keep my pH stable?

Postby Denali » Sun 26 Jul, 2009 01:10

Oregonmommy wrote:Chlor. 2-3
TA- 80
Ph- 6.8 -7.2 closer to 7.2
How do I keep my pH stable. I added some pH plus and got it at 7.4 but after a few days it dropped back down even with everything else staying in normal range.


Hi,

Are you using chlorine tablets in your pool?
Oregonmommy
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My Pool: 15' round 42 " deep abouve ground pool
Location: Oregon

How do I keep my pH stable?

Postby Oregonmommy » Sun 26 Jul, 2009 10:54

Yes I use the 3 in 1 3" tablets.
Denali
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How do I keep my pH stable?

Postby Denali » Mon 27 Jul, 2009 01:45

Oregonmommy wrote:Yes I use the 3 in 1 3" tablets.


The tablets are acidic and lower pH so your pH is likely to always be on the low side. 7.2 is OK but 6.8 isn't. You can try turning your return lines up to help aerate the pool. This will cause the pH to rise so may balance out the tablets.

Sounds like you're using test strips to do your testing? A drop based pH test would be better for you so you get a more exact reading. If you have any water features (waterfall etc) in your pool you can use those to help keep pH up.
chem geek
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How do I keep my pH stable?

Postby chem geek » Mon 27 Jul, 2009 10:02

Increase the Total Alkalinity (TA) level as well. If you use pH Up (Arm & Hammer Super Washing Soda; soda ash; sodium carbonate), then this will raise both the pH and the TA. You didn't list your Calcium Hardness (CH) level. If this is a vinyl pool and the CH is low, then raising the TA quite a bit higher will not be a problem and will help compensate for the acidity of the Trichlor.

Note that with continued use of Trichlor, you will build up Cyanuric Acid (CYA) in your pool. For every 10 ppm Free Chlorine (FC) added by Trichlor, it will increase CYA by 6 ppm. Even with a low 1 ppm FC per day chlorine usage, using Trichlor alone will raise the CYA by over 100 ppm in 6 months unless there is significant water dilution. The higher CYA will require a higher FC or use of a weekly algaecide (e.g. PolyQuat 60) or a phosphate remover to prevent algae growth, and may require frequent shocking and/or use of a clarifier to keep the water clear as the chlorine takes longer to oxidize bather waste when the FC/CYA ratio is lower.
Oregonmommy
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My Pool: 15' round 42 " deep abouve ground pool
Location: Oregon

How do I keep my pH stable?

Postby Oregonmommy » Tue 28 Jul, 2009 12:24

Would it be better then to use the chlorine granuals?
Denali
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How do I keep my pH stable?

Postby Denali » Tue 28 Jul, 2009 13:59

Oregonmommy wrote:Would it be better then to use the chlorine granuals?


The two most common granular chlorine products are di-chlor and cal hypo. di - chlor also increases CYA levels like the tablets do. Cal hypo will increase your calcium hardness over time.

Liquid chlorine or bleach is what I like to use. Cal hypo is probably your best bet if you need to use a granular.
czechmate
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My Pool: 16 x 32 gunite21000 gal., Diamond Brite Blue, Swimquip XL pump, DE36
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How do I keep my pH stable?

Postby czechmate » Thu 30 Jul, 2009 16:08

Question for Richard:

I am trying to find what will benefit the new Diamond Brite plaster for along run and also make it easier to maintain the pool. I have added 55lb of boric acid to a new fill of 2100 gallons. Now I have also found that I can raise the TA by adding Borax.
My question is about the SALT CONTENT in the pool water.
Is it good to have some or should I just disregard it?
What would be the benefits to a swimmer or to the maintenance of the pool if any?
Thanks,
Ivan
czechmate
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How do I keep my pH stable?

Postby czechmate » Thu 30 Jul, 2009 16:09

There was a typo: the pool is 21000Gal.
Ivan
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How do I keep my pH stable?

Postby chem geek » Thu 30 Jul, 2009 21:58

Ivan,

You need to have enough calcium, in combination with TA and appropriate pH, to have the saturation index near zero in order to protect your plaster surface (the Diamond Brite rock aspect doesn't matter in this regard). Use The Pool Calculator to calculate dosages and for the saturation index.

Don't raise the TA too much if you are going to be using chlorinating liquid or bleach as your primary source of chlorine. If your pH tends to rise, then your TA is too high and vice versa.

Since chlorine will tend to increase the salt level over time, I wouldn't try raising it. Some people add salt for a saltwater pool feel without the actual salt cell equipment and you could certainly do that if you wanted to (around 1500 ppm is what most people shoot for without an SWG cell), but only dilution will reduce the salt level and if you have porous stone material for coping or hardscape, you might need to seal it (splashed out salt can be an issue, depending on the amount, whether it rains, etc.).

Richard

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