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Thread: MY CH keeps going up

  1. Back To Top    #1

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    MY CH keeps going up

    I am not sure what the issue is, but about a month ago I had my CH at 330. Tested yesterday and CH is around 400.

    So not sure what the issue is here.

    TA=90-100
    FC=5-6
    CH=400
    CC=0
    CYA=30-40

    I had to fill the pool and tested my fill water, but since it is not mixing now sure how accurate it is.

    Fill Water

    FC=0
    CC=1-1.5 (cant remember off the top of my head)
    TA=380-400
    CH=30-40
    Did not test for CYA

    So can some tell me what may be going on?

    Thanks.
    13,000 Plaster IG Pool approx
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    Re: MY CH keeps going up

    To make sure, you are not using any calcium hypochlorite for chlorinating purposes are you?

    Your fill water does have calcium in it, but I don't suspect that to be the reason because that would require quite a bit to raise your calcium hardness to that degree.

    The only thing that I can think of is that you may be having some variance in your test results because of differences in endpoint perception. When you do your test, are you getting a fading result such a a very light purple or are you getting all the way to blue? Also, what sample size are you using to test? You should probably be using the high concentration sample size which is 10 ml instead of the low concentration sample size which is 25 ml. Your result of 330 ppm could only come from the 25 ml sample since the 10 ml sample one would only produce results in 25 ppm increments (300, 325, 350, etc.). Always use the 10 ml sample test because you use less reagent this way and accuracy down to 5 ppm is not required.

    Test again and make sure that you are getting all the way to blue as your endpoint. See the link below for some specifics regarding this test too.

    http://www.taylortechnologies.com/Chemi ... ntentID=70

  3. Back To Top    #3
    JasonLion's Avatar
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    Re: MY CH keeps going up

    When was your pool plaster applied? If it is less than one month old, it is the plaster curing that is raising the CH level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  4. Back To Top    #4

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    Re: MY CH keeps going up

    Quote Originally Posted by 257WbyMag
    To make sure, you are not using any calcium hypochlorite for chlorinating purposes are you?

    Your fill water does have calcium in it, but I don't suspect that to be the reason because that would require quite a bit to raise your calcium hardness to that degree.

    The only thing that I can think of is that you may be having some variance in your test results because of differences in endpoint perception. When you do your test, are you getting a fading result such a a very light purple or are you getting all the way to blue? Also, what sample size are you using to test? You should probably be using the high concentration sample size which is 10 ml instead of the low concentration sample size which is 25 ml. Your result of 330 ppm could only come from the 25 ml sample since the 10 ml sample one would only produce results in 25 ppm increments (300, 325, 350, etc.). Always use the 10 ml sample test because you use less reagent this way and accuracy down to 5 ppm is not required.

    Test again and make sure that you are getting all the way to blue as your endpoint. See the link below for some specifics regarding this test too.

    http://www.taylortechnologies.com/Chemi ... ntentID=70
    No the only thing I have added to my pool lately has been bleach and acid. I added some cya to bring that up, and a month or so ago added stuff to bring up the CH from around 100. Since I have added the cya and CH up stuff, I have only added the bleach and acid.

    When I test, I make sure the endpoint turns blue, not when it is almost blue. I also do another drop after it is blue to see any change. I have been following the directions that come with the tftestkit on the kit itself. So instead of filling to 25 ml I should fill to 10 mil and multiply each drop by 25 instead of 10?
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  5. Back To Top    #5

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    Re: MY CH keeps going up

    Quote Originally Posted by JasonLion
    When was your pool plaster applied? If it is less than one month old, it is the plaster curing that is raising the CH level.
    The pool plaster is not new. I would say it is fairly old, around 5-7 years if not more. Was not able to get much info about the pool from when we bought the house in September of last year.
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  6. Back To Top    #6

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    Re: MY CH keeps going up

    Quote Originally Posted by mynewpool
    So instead of filling to 25 ml I should fill to 10 mil and multiply each drop by 25 instead of 10?
    If you use a 10ml sample for the CH test, you use 10 drops R-0010, 3 drops R-0011L, and then each drop of R-0012 is multiplied by 25.
    --paulr
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  7. Back To Top    #7

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    Re: MY CH keeps going up

    Quote Originally Posted by PaulR
    Quote Originally Posted by mynewpool
    So instead of filling to 25 ml I should fill to 10 mil and multiply each drop by 25 instead of 10?
    If you use a 10ml sample for the CH test, you use 10 drops R-0010, 3 drops R-0011L, and then each drop of R-0012 is multiplied by 25.
    --paulr
    Thanks, I will give that a try.
    13,000 Plaster IG Pool approx
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  8. Back To Top    #8

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    Re: MY CH keeps going up

    Ok did the 10 ml sample and got 375. We have had a lot of rain on last Friday and then on Monday. I really do not want to have to drain if possible. I use bleach for chlorine and have not had to add acid for a while now due to what seems like a stable pH level.

    These test were done yesterday via TF100 kit at home. Water temp is around 83-85.

    pH-7.5
    FC-6
    CC-0-.5(.5 last night due to the rain I assume. Usually it is 0)
    TC-6.5
    TA-90-100
    CH-375
    CYA-40
    13,000 Plaster IG Pool approx
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  9. Back To Top    #9

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    Re: MY CH keeps going up

    I don't see any reason for you to change out water. Your CH of 375 gives you a CSI right around 0.15 with all other things considered. If you lowered your TA a touch, say, to 80, that would help even more.

    There are other s on here who live in the arid southwest and must contend with higher CH levels than most of us in Texas could ever dream of and they can be quite successful in managing their high CH water by closely watching their TA and pH. You can experiment with this by manipulating the values on the pool calculator. Give it a try.

  10. Back To Top    #10

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    Re: MY CH keeps going up

    A little off the topic, but I noticed that with my TA at 90-100, my pH level has been farely stable. I have read the TA is used to stablize pH levels, but mine has not seemed to change even with two very heavy rains. It is right around 7.5 or so. Each day I do the test the color seems to be the same which makes me happy as I do not have to add acid and take the chance of TA coming down more. So is this something that is normal. The test color seems to be around a light to semi dark orange which is around 7.5
    13,000 Plaster IG Pool approx
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  11. Back To Top    #11

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    Re: MY CH keeps going up

    Sounds like you have your TA in a good spot for your pool.

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