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Thread: Ph shoots up

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    teppy's Avatar
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    Ph shoots up

    My pool was completed in November '07. since then, I have lots of trouble keeping my Ph down. I use the pool calculator and the test kit from here. I know that newer plastered pools have high Ph, but for how long? Mine is about 7 months old now. My alkaline used to stay between 100-120, but now that is staying around 130. I keep adding dry acid according to the pool calculator. How long can I expect this to go on?
    17,000 gallon roman shaped gunite pool-AquaRite goldline SWG

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    JasonLion's Avatar
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    Re: Ph shoots up

    PH will rise from the plaster curing for about one year. PH can also rise if you have high TA levels and a source of aeration, such as a SWG.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    Re: Ph shoots up

    Please post a full set of test results so we have a better idea of what is going on. Also some details about your pool would be helpful also such as kind of filter, what type of chlorine you are using, and what kind of chlorine you are shocking with.

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    teppy's Avatar
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    Re: Ph shoots up

    My test readings are:
    5/24/08
    FC-4
    CC-0
    TC-4
    Ph-7.6
    TA-120
    CH-260
    CYA-42
    temp-79

    5/25/08
    FC-3
    CC-0
    TC-3
    Ph-7.6
    TA-110
    CH-260
    CYA-42
    temp-80

    5/28/08
    FC-1.5
    CC-0
    TC-1.5
    Ph-8.0
    TA-110
    CH-
    CYA-
    temp-82

    6/6/08
    FC-1
    CC-0
    TC-1.5
    Ph-8.2
    TA-160
    CH-240
    CYA-55
    temp-83

    6/10/08
    FC-1.5
    CC-0
    TC-1.5
    Ph-7.8
    TA-150
    CH-290
    CYA-43
    temp-85

    6/14/08
    FC-20
    CC-0
    TC-20
    Ph-7.4
    TA-110
    CH-280
    CYA-
    temp-85

    From 5-24 to 5-25, there was not much change in 24 hours. You can see that 3 days later on 5/28 how the ph goes up. I did do daily checks between 5/28 and the next complete test date of 6/6 to get the Ph down. I just don't record those days that I only do chlorine and Ph. On 6/6 it went up pretty high again, and of course I did add acid to get it back down within range. Again on 6/10 its starting to go up again. I had never shocked my pool until last week. I was hoping that it would kill lots of water bugs, and it didn't. You can see how high my chlorine got on 6'14. I checked this am and my chlorine is down to 5 and my Ph was not bad at 7.6, but my TA was at 130. I added acid this morning because I knew that my Ph would be on its way up. I do have a raised bond beam with two sheer descents so there is alot of aeration. I have a pentair Challenger 1.5 hp pump with pentair triton TR60 sand filter. I have polaris 280 that runs everyday. I use a chlorine feeder with the round pucks.
    17,000 gallon roman shaped gunite pool-AquaRite goldline SWG

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    JasonLion's Avatar
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    Re: Ph shoots up

    If you lower your TA down to between 70 and 90, the rate of PH increase will be noticably slower.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    teppy's Avatar
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    Re: Ph shoots up

    I can't figure how much acid to add to get my TA down that low. Could you please tell me how much? Using the pool calculator, I enter a Ph goal of 7.4 with the now reading of 7.6 and a TA goal of 90 the now reading of 130 and it tells me to add 23oz of dry acid. Is this right? Thats seems like alot. Did I do this right?
    17,000 gallon roman shaped gunite pool-AquaRite goldline SWG

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    JasonLion's Avatar
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    Re: Ph shoots up

    Yes, you are doing the calculations correctly. For this relatively small PH change you could go ahead and add that all at once. For larger PH changes it is best to add less than you calculate you need, wait an hour, and then test again to see where you ended up. All of the measurements are somewhat approximate and PH calculations are themselves approximate, so it is good to take a little care until you get a sense of how your pool reacts.

    For the procedure to lower TA see this article from Pool School or the more detailed write up here.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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