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Thread: alkalinity

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    I have a 24000 gallon salt water vinyl liner pool with a chlorine generator. I just added some baking soda to increase my alkalinity and I am asking myself why. My levels are as follows:

    salt 3000 ppm
    pH 7.7
    alk 50 ppm
    free chlorine 3.5 ppm
    cya < 20 (I will be bringing that up shortly)

    The thing is, my pH just doesn't change much. If anything it tends to the high side of the acceptable range. The bicarbonate is going to shift the equilibrium to a higher pH and I am not sure I want that. Isn't chlorine more effective at a lower pH, say 7.4 than it is at 7.8?

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    duraleigh's Avatar
    Join Date
    Apr 2007
    Sebring, Florida

    Re: alkalinity

    baking soda will have little, if any effect on your pH.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: alkalinity

    As soon as there is any CYA in the water the whole chlorine more effective at lower PH thing stops being true, or rather becomes such a small effect that you can completely ignore it. For various other reasons, it is best to let the PH settle around 7.7 or 7.8 and TA around 60.

    You don't want TA to be too low or PH can fluctuate way too easily. 50 is right on the edge of acceptable, though I recommend 60.

    And obviously you need to raise your CYA level, which will bring the PH back down.

    Don't try to micro-manage the PH. It is going to change a bit every time you add any chemical. If you try to keep tight control over it you will just end up adding unnecessary chemicals or worse not adding something your need. Just let the PH wander between 7.5 and 7.8 and adjust it if it is going to go out of that range and you will be fine.
    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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