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Thread: Question about CH

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    Question about CH

    I have an 18x36 inground pool with a vinyl liner. Most everything I have read is that you can ignore any CH readings. In general my readings have come back very low, usually 0-20. Is there really any value too low for a vinyl lined pool?

    But more importantly, my deck around the pool is made of stamped concrete, and anytime anyone is in the pool the first foot or so of decking around the pool is constantly wet. This is usually about an hour or so most days, but is often up to 8 hours several times a month. Is there any leaching or damage to the concrete being done if the CH in the pool is very low? What would the recommended value be to prevent concrete damage? The concrete does have many pre-cut channels to prevent frost damage, so the water easily gets to more than just the top surface.

    Thanks.

    Kevin
    22,468 gallons, IG, 18'x36' vinyl, Pentair FNSP 36 DE filter, Stenner 45MHP10 pump with 15 gallon chlorine tank, TF-100 Test Kit

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    duraleigh's Avatar
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    Re: Question about CH

    Welcome to the forum. I doubt you are incurring any damage at all. It would take constant exposure over a long period before you would notice any deterioration.

    Are you testing CH with strips? That is VERY unusual for your calcium to really be that low and I would question the test result unless you're filling the pool with softened water.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Question about CH

    We generally advise that with vinyl lined pools, low CH is of no significance. However, a high CH is bad for all pools due to the scaling risk on surfaces. Even a vinyl lined pool can have problems with a high CH due to scaling on equipment parts, particularly heaters. I agree with duraleigh though in that it is a rare exception to see a pool with a low CH like that.

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    Mod Squad Bama Rambler's Avatar
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    Re: Question about CH

    Wlecome to the wonderful world of low CH (mine runs about 10ppm)!

    We're definitely in the minority. I don't worry about it. Then again, I don't have concrete decking. I still probably wouldn't worry about it.
    Dave J. TFP Moderator
    24' x 52" Round AGP. 2hp/¼hp SPL Power-Flo 2-speed pump. 200sqft Waterway Cartridge Filter. 45MHP2(3GPD) Stenner Peristaltic Pump
    Pool School ----- Pool Math ----- TF-Test Kit

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    Melt In The Sun's Avatar
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    Re: Question about CH

    don't worry about it; rainwater has zero CH and nobody worries about that
    11,200 gal, Pebble-Tec; Tristar 2-speed 1hp - Swimclear 325 ft2 cart - SWG - A & A in-floor cleaner - Heat pump. For the poolside cooking, a Yoder Wichita and a Big Steel Keg!
    TF Test Kits -- PoolMath -- Pool School
    Make each day your masterpiece. - John Wooden

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    Re: Question about CH

    Quote Originally Posted by Melt In The Sun
    don't worry about it; rainwater has zero CH and nobody worries about that

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    Re: Question about CH

    For the record, I test with strips and a TF-100 test kit. Always low. I took the same water to two local pool stores (I needed some muriatic acid to lower the PH) and one store, which used strips and some enclosed strip reader said it was 200; the other store, using a chemical test of some sort, read it at 50. That's what prompted me to buy a TF-100 kit of my own.

    Anyway, thanks for the advice. I'll stop worrying about it unless it gets too high.
    22,468 gallons, IG, 18'x36' vinyl, Pentair FNSP 36 DE filter, Stenner 45MHP10 pump with 15 gallon chlorine tank, TF-100 Test Kit

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