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Thread: First time question about Calcium Hardness

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    First time question about Calcium Hardness

    OK I started looking at TFP for a couple of years and started BBB last year. I truly loved the results I got last year. This year I drained my pool some and add water. I have a Stonescapes plaster pool and it is 25,000 gallons. I live in north Fort Worth, TX. Here are my test results:

    FC= 2.0
    CC= 0.0
    pH= 7.6
    TA= 90
    CH= 200
    CYA= 40

    My question is: should I be raising calcium hardness right away, or can I live with this without doing anything for awhile?

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    Mod Squad jblizzle's Avatar
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    Re: First time question about Calcium Hardness

    Welcome to TFP!!!

    You can wait if you keep your pH a little higher (like above 7.5). Use PoolMath and look at the CSI ... keep that near zero and your plaster will be fine with the lower CH.

    When I refilled, my CH was 130ppm ... now a year later it is 270ppm ... and I would expect that next spring it will be around 400ppm.
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    Re: First time question about Calcium Hardness

    Thanks for the quick reply!!!
    I do seem to keep the pH around 7.6 and 7.7 throughout summer. Thanks again.

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    BoDarville's Avatar
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    Re: First time question about Calcium Hardness

    Welcome to TFP!

    Might also be worth your while to test the CH of your fill water to get a baseline. I agree with jblizzle in that I would keep your pH slightly higher as opposed to adding CH. Most all fill water has CH in it to varying degrees. Whenever you add water to a pool, you are also adding some CH. The water evaporates, but calcium does not. Therefore, the concentration of CH rises with time. It will eventually stabilize, but the level at which it stabilizes depends on your fill water's CH level and the amount of rain you get (rainwater has no CH in it).
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    Patrick_B's Avatar
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    Re: First time question about Calcium Hardness

    Adding to comments from the fine Gentlemen above, you will be fine with that CH and the pH they suggest. No worries.
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    pwrstrk's Avatar
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    First time question about Calcium Hardness

    For a CYA level of 40 your FC of 2 is below the min. The lowest your FC should ever be is 3 for that CYA level. Letting it fall below the min is risking an algae outbreak.
    You should be targeting 7 and that would give you wiggle room so you don't fall below your min. 😎
    Jeff
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    Patrick_B's Avatar
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    Re: First time question about Calcium Hardness

    Quote Originally Posted by pwrstrk View Post
    For a CYA level of 40 your FC of 2 is below the min. The lowest your FC should ever be is 3 for that CYA level. Letting it fall below the min is risking an algae outbreak.
    You should be targeting 7 and that would give you wiggle room so you don't fall below your min. ��
    Good catch, and thanks Jeff!
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    Re: First time question about Calcium Hardness

    I did not even know that calcium hardness was important. What should CH be kept at? I have an attached spa to my pool. Off the top of my head i remember having these levels......

    Im currently SLAMing
    PH ?
    FC 16
    CC 0.5
    CH 100
    TA 100
    CYA 30
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    In-ground gunite 17,400 Gal, FNS plus 60 DE Filter

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    Patrick_B's Avatar
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    Re: First time question about Calcium Hardness

    For a Gunite type pool like yours about 250-450 is the range. On the low end, 200 isn't cause for alarm, but will be about as low as you'd want to go.
    Reason being, that if there is too little CH in the pool, the water is more aggressive and will dissolve the calcium your plaster based finish over time.

    On the high end, once you reach 450-500, you have to manage the pH a little more carefully and not let it drift too high, with 7.8 being the ceiling. Many people have much more and have to be extremely careful manage the pH very closely, because the calcium will come out of the water and create scale on the pool's interior surface. High pH is a catalyst for this, so it makes scaling a much more likely problem. High pH and high CH do not go well together at all.

    You should check your fill water just to find out where you stand. If it is low, you'll need to add some calcium to the pool. Many of us wish we could trade places with you as our water sources are overloaded with it.

    Levels outside these ranges are mostly a non concern in a vinyl type pool, as there is nothing to deteriorate, and calcium doesn't adhere readily to plastic to form scale.

    I answered here as this was on the subject, but if you wish to know more, please start a thread of your own and we can address you specifically.
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    Re: First time question about Calcium Hardness

    Thank you sorry.... it was a crawfish weekend
    Century B129, 3/4 HP, 1.5 SF,
    In-ground gunite 17,400 Gal, FNS plus 60 DE Filter

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