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Thread: Calcium hardness and vinyl liners

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    Calcium hardness and vinyl liners

    I just took a water sample to the pool store so that I could use the results to improve my test color interpretation skills. The store measured my calcium hardness at 150 and recommended I add hardener. As I had learned on this wonderful site, I replied that since I have an above ground pool with a vinyl liner this was not an issue and I was happy with the 150 level. The answer to this was that the ideal calcium hardness doesn't entirely have to do with the pool surface, it's about what the water "needs". The salesperson said that the water needs calcium and if it doesn't have enough it will acquire it, suggesting that the water would leech it from the swimmers. I actually had to hold back a laugh. I wish at the time it had occurred to me to point out that to protect her bones perhaps she should never take another shower.

    So my question... Am I understandig this site correctly, there is no need to tend calcium hardness in vinyl pools? Is there any consideration beyond pool surface that applies to maintaining calcium hardness?

    As always, thanks for all the insight!

    Above ground 24' 13,500gal

    TH 150
    FC 5
    pH 7.8
    TA 80 --> working on it with pool calculator
    CYA 50
    13,500 GAL half buried Doughboy AG Vinyl, 24' Round, DE filter

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    Mod Squad Bama Rambler's Avatar
    Join Date
    Jun 2009
    SouthWest Alabama

    Re: Calcium hardness and vinyl liners

    In a vinyl pool you don't have to worry about low CH only high. The only reason to worry about it would be if you had a piece of equipment that the warranty hinged on the CH being maintained at some level.
    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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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Calcium hardness and vinyl liners

    Yep, what Bama Rambler said.
    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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    SinistrV6's Avatar
    Join Date
    Sep 2008
    Mississippi Gulf Coast

    Re: Calcium hardness and vinyl liners

    I, too, have ignored my "0" CH readings. My neighbor was taking her pool water to be sampled (I do my own sampling) and offered to take mine with her. I was curious as to how my results would compare and sent the sample with her. None of the results or recommendations surprised me but they suggested adding 80# of Calcium Chloride Flake to raise my CH to their recommended 174-350ppm range. When I told my neighbor that CH isn't a necessity in a vinyl pool, she said it helps to stabilize the other chemicals and has helped her keep her pool looking good.

    Any thoughts on this? BS? Fact? Fiction? Old wive's tale?
    42X16X24 True-L vinyl lined IG pool
    30,500 gallons
    Pool Pilot Digital SWG
    Sand filter

  5. Back To Top    #5

    Join Date
    Mar 2007
    San Rafael, CA USA

    Re: Calcium hardness and vinyl liners

    CH does not stabilize other chemicals and is not needed to make a pool look good. Too low a CH can have a pool have more foaming, but usually it's a spa where this is an issue since there is far more aeration. Around 120-150 ppm CH helps to eliminate foaming in a spa, but is not usually needed in a pool.

    Calcium is only needed in a pool or spa when one is trying to saturate the water with calcium carbonate -- that is, adjusting pH, TA, CH (and temp and CYA) to have a zero saturation index -- for the purpose of preventing calcium carbonate from dissolving from plaster surfaces and grout between tile. If there is no calcium carbonate in a surface exposed to the water, then there is no need for such calcium carbonate saturation. It's as simple as that.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
    12 Fafco solar panels; Purex Triton PowerMax 250 natural gas heater (200,000 BTU/hr output); automatic electric pool safety cover; 4-wheel pressure-side "The Pool Cleaner"

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