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Thread: Can water temp greatly affect test results?

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    Join Date
    Jul 2007
    Location
    Florida
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    Can water temp greatly affect test results?

    Here's a sample reading during cooler temps in March:

    FC 10
    pH 7.5
    TA 90
    CH 290
    CYA ~80

    Haven't done anything drastic with pool except bleach/acid maintenance for FC. Maybe a little fill water once a month, but no leaks. Water always crystal clear. Now here's my readings as of today with water temp a LOT warmer:

    FC 8
    pH 7.4
    TA 70
    CH 340
    CYA ~55

    Don't have exact water temp readings, but I can't explain the changes in TA, CH, CYA. Never drained any water, never added calcium, never aerated or anything. Water still always cystal clear so forgive me if this seems like nitpicking. Just curious if higher temps have a tendency to exhibit lower TA/higher CH/lower CYA readings.
    22,000 gal in-ground, 3-8ft
    Cartridge filter
    Pebble Tec resurfaced
    Polaris 360

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    JasonLion's Avatar
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    May 2007
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    Water temperature changes mostly only affect PH, perhaps change the TA slightly. Water temperature will not affect CH or CYA levels at all. Water temperature can affect the CH and CYA tests a little. When the water is fairly cold you need to mix longer during the CH and CYA tests to get accurate results.

    Do you have an auto fill system or an automatic overflow drain? Either of those could result in water replacement without you noticing.
    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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    frustratedpoolmom's Avatar
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    Did you test the water or was it the pool store?
    Helpful links: Pool School; CYA/Chlorine Chart
    24' round AG pool, 52" high, Raypak heater; Waterway 2 spd Pump;
    150 Sq ft. Clearwater Cartridge Filter; Former and DISSATISFIED "Pool Frog" owner
    http://www.PerfectlyClearPoolService.com

  4. Back To Top    #4

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    All testing is with the trusty ole TF100 Fill water is straight from the tap, no automatic systems or drains.

    Accounting for about +/-10% error factor, I suppose my readings are still fine. And I know TA and CYA levels have about a 30% correlation due to carbonates.

    I've come a looong way with CYA. Used to be way past 100+ last summer. Now it's 55... with no draining. Guess water replacement is much more prevalent than I thought.
    22,000 gal in-ground, 3-8ft
    Cartridge filter
    Pebble Tec resurfaced
    Polaris 360

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