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Thread: Does pool water get stale? I have constant ALK drops and PH increases

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    Join Date
    Mar 2007
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    Virginia Beach
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    Does pool water get stale? I have constant ALK drops and PH increases

    I have a 6K gallon fiberglass pool. Have had the same water other than rain and top ups for many many years. Never done a full drain. I chlorinate with bleach (Liquidator). I keep all my numbers pretty perfect. TA 110ish, PH 7.4, CYA 40-50, CL 4-6.

    Starting about 2 years ago I developed this ALK decrease, PH increase issue. I would say I lose 10PPM ALK per week and PH prob goes from 7.4 to 8.3 each week. Also had a wild scale outbreak earlier this summer that I had to sand off the pool. Water looks perfect right now other than the two creeping chemmies that I mentioned.

    Haven't changed my pool filter sand in about 5 yrs. Was planning to do it this fall.

    Any ideas? Normal? Does water just get stale after awhile? Considering doing a 3/4 drain and refill this fall.
    6000 gal inground fiberglass
    1.5hp pump / sand filter
    Liquidator

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    Re: Does pool water get stale? I have constant ALK drops and PH increases

    The problem is that you're keeping the TA too high and the pH too low. The combination creates excess CO2, which causes ph rise. When the ph rises, you add acid to lower the ph, but that also lowers the TA, so you add bicarb and the cyle begins again.

    Try TA at 60 and ph at 7.8.

    NaHCO3 + HCl <> NaCl + CO2 + H2O

    Sodium bicarbonate + hydrochloric acid = salt + carbon dioxide + water.

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    Join Date
    Mar 2007
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    Virginia Beach
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    Re: Does pool water get stale? I have constant ALK drops and PH increases

    Isn't 60 low? I have always tried to keep TA around 100. Used to be able to keep it there too. But not anymore.
    6000 gal inground fiberglass
    1.5hp pump / sand filter
    Liquidator

  4. Back To Top    #4

    Re: Does pool water get stale? I have constant ALK drops and PH increases

    The best TA is whatever keeps your pH stable. If your ph keeps going too high, your ta is too high. If your ph keeps going too low, your ta is too low. When the ta is right for your pool, the ph will be very stable.

    Try TA at 80 and ph at 7.8. If the ph keeps going too high, lower the ta again.

  5. Back To Top    #5
    Mod Squad YippeeSkippy's Avatar
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    Jan 2012
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    'burbs of Augusta, Georgia
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    Re: Does pool water get stale? I have constant ALK drops and PH increases

    Don't bother changing your sand out- it never wears out in your lifetime and only rarely needs changing (such as converting a pool from Bacqua to Chlorine).
    My Amazon Smile for November12K Fiberglass IG, Infinity 4000 automatic cover, SWCG, Hayward Sand Filter, Hayward 1.5 Pump, Doheny Discovery Robot, Savi Melody LED pool lights, outdoor speakers and other assorted doo-dads. Sundance Altamar Hot Tub.
    Our pool build--> Our Pool Solved Our Sloping Yard Skippy's Cheap Pool Cooler -->Skippy's New Fountain

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