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Thread: CH

  1. Back To Top    #1


    Got a question! What would make the CH level in my pool go from 300+ to 200? All my other numbers look ok, except for my CH.

    Thanks for the help.
    27100 gallon in ground Pool/Spa, SWG, Pebble Sheen-Aqua Blue, (All Pentair Equipment) Pentair VS Pump, Cartridge- filter, build completed Dec. 2013, Houston, Texas

  2. Back To Top    #2
    Mod Squad jblizzle's Avatar
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    May 2010
    Tucson, AZ

    Re: CH

    First things that pop in my mind is a leak that is masked by an auto fill line that has soft water?
    Or testing error?

    Not really any other options.
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  3. Back To Top    #3
    JasonLion's Avatar
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    May 2007
    Silver Spring, MD

    Re: CH

    Anything that replaces water will tend to lower CH, backwashing, splash out, overflow, etc.
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  4. Back To Top    #4
    Patrick_B's Avatar
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    Jun 2011
    Midland TX

    Re: CH

    Test your fill water and see what the CH is. Since Blizzle mentions it, do you have a softener anywhere around? If it went down, dilution is the only way it could have.
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  5. Back To Top    #5
    BoDarville's Avatar
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    Jun 2012
    DFW, Texas

    Re: CH

    Another possibility is rainwater which will dilute the pool water with calcium-free water, although it would take a good amount of rainfall to lower the CH dramatically. A passing shower will have little effect. Considering the dramatic drop from 300+ to 200, it could be a combination of rainfall and one or more of the factors mentioned above.

    A follow-up question...How much time elapsed from the CH test of 300+ to the current result of 200?
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  6. Back To Top    #6

    Re: CH

    2 weeks. We have had a lot of pollen and some rain. So I thought maybe it was a combination, being a rookie! So I waited and retested and it is still at 200.
    27100 gallon in ground Pool/Spa, SWG, Pebble Sheen-Aqua Blue, (All Pentair Equipment) Pentair VS Pump, Cartridge- filter, build completed Dec. 2013, Houston, Texas

  7. Back To Top    #7
    vcarnett's Avatar
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    May 2015

    Re: CH

    I also came here for this question as mine is dropping, though not so dramatically. Just my 2 cents and I see this post is old:

    Typically, taps on the outside of the house are not supplied from water softener treated water. The lines to the bibs come from the water source before it reaches the softener as it's not good for lawn and garden. So you should be able to rule that out.

    As mentioned above, Rain will effect as will splash-out (resulting in lower Calcium top off - as mentioned, test your tap). I was very surprised to find that my fill water (from the tap) is only 50ppm CH (and I'm in Austin - I thought we had really hard water). Mine dropped from 140 to 120 in just a couple days due to rain (but that was a couple inches of rain).
    Anthony Sylvan 17k gal free form IG Gunite. 3' - 6'. Waterway SVL56 Pump. Pentair FNSP 48 (sq ') DE Filter (2013). Polaris 280 sweep w/Polaris PB4 booster. 2 skimmer intakes and 2 deep-end intakes. 4 returns. Pool Installed 2010. Filled from city water (Austin, TX - CH 50ppm. pH 9.0). Taylor k-2006 test kit. Currently running the pump 6 hrs / day.

  8. Back To Top    #8
    Richard320's Avatar
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    Jan 2010
    San Dimas, CA (LA County)

    Re: CH

    If you haven't been good about keeping pH in line, the dissolved Calcium could be sticking to the walls in the form of scale. Plug your numbers into poolmath and see what the CSI is.
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