How can I maintain a steady PH level?

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
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meatloaf
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How can I maintain a steady PH level?

Postby meatloaf » Thu 15 Apr, 2010 13:51

I have an inground plaster pool and my PH seems to rise daily. I have to add 4.5 oz of 31% muriatic acid daily to maintain 7.5. What could the problem be?
CL 3
TA 70
CH 550
CYA 40
Temp 74*
Thanks


chem geek
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How can I maintain a steady PH level?

Postby chem geek » Thu 15 Apr, 2010 21:57

Do you have a saltwater chlorine generator (SWG)? Do you have a lot of aeration of your water such as waterfalls, fountains, spillovers, etc.? What is your source of chlorine, assuming that is what you are using for sanitation?
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meatloaf
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Location: Gilbert AZ

How can I maintain a steady PH level?

Postby meatloaf » Thu 15 Apr, 2010 22:39

I don't have a SWG, using 10% liquid chlorine and none of the fountains, waterfall or areators are turned on.
chem geek
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How can I maintain a steady PH level?

Postby chem geek » Fri 16 Apr, 2010 00:11

Has it been raining? If not, then I'm not sure why your pH is rising so quickly unless the chlorinating liquid you are using has a very high amount of excess lye in it. There is another possibility, however. How old is your plaster pool or if it was replastered, how recently was that?
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meatloaf
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Location: Gilbert AZ

How can I maintain a steady PH level?

Postby meatloaf » Fri 16 Apr, 2010 08:37

It hasn't rained for a couple of weeks. The pool is about 15 years old and has never been replastered. I have the same problem when I use Tri-chlor 3" pucks.
chem geek
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How can I maintain a steady PH level?

Postby chem geek » Fri 16 Apr, 2010 10:34

The pH rises even when you use Trichlor pucks? That is very strange indeed since they are quite acidic and usually people have to add pH Up to restore pH and TA.

Is it possible that your TA reading is wrong? How are you making these measurements? Are you using a Taylor K-2006 test kit or are you using test strips or getting readings from a pool store? Are you adding any chemicals to the water other than chlorine?
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meatloaf
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Joined: Sat 07 Jul, 2007 13:20
My Pool: 10,500 Plaster pool. Sta-Rite HRPB 30 Sand filter, 13 in floor Quik-Klean pop up jets.
Location: Gilbert AZ

How can I maintain a steady PH level?

Postby meatloaf » Fri 16 Apr, 2010 10:39

I am using the Taylor K-2005 test kit. I am not adding any other chemicals.
chem geek
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How can I maintain a steady PH level?

Postby chem geek » Fri 16 Apr, 2010 18:50

Well, I've run out of ideas. You could try letting the TA drop down to 50 ppm and see if that changes the rate of pH rise. If it does, then it's carbon dioxide outgassing, though without aeration I don't see why it would be high. If you do find that a lower TA is more stable or requires less acid to compensate for the pH, then you could raise the CH level to compensate for the saturation index and you can use 50 ppm Borates as an additional pH buffer (which will slow down pH rise, but won't lower the amount of acid you need to add so is only useful if the lower TA results in less total acid needed per time).
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meatloaf
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My Pool: 10,500 Plaster pool. Sta-Rite HRPB 30 Sand filter, 13 in floor Quik-Klean pop up jets.
Location: Gilbert AZ

How can I maintain a steady PH level?

Postby meatloaf » Fri 16 Apr, 2010 20:22

I just tested the TA again using my magnetic stirrer and came up with the same number, 70. I'll try dropping the TA to 60 and see if that helps. If not I'll take it down to 50.
Thanks for all your help!
SteveM1800
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How can I maintain a steady PH level?

Postby SteveM1800 » Wed 28 Apr, 2010 12:59

In order to make everthing else balanced the ph needs to be right first. When you get the ph between 7.2 to 7.8 try adding alkalinity. Its is a ph buffer which means that if you ph drops down the alkalinity will raise it back up to normal again that way your not raising the ph on a daily basis. Check it out on our website 1800pools.com.

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