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Thread: Acid Consumption Seems High

  1. Back To Top    #1

    Join Date
    Jan 2009
    Wollongong Australia

    Acid Consumption Seems High

    Hi Everyone,

    I'm a new pool owner (purchased house with existing pool, kids love it). I've got the water chemistry levels in range according to my local pool shops, but the pool needs 250 mL of acid every day to keep the pH in the recommended 7.4-7.6 range. Any suggestions on how to reduce the chemical consumption and maintenance effort would be appreciated.

    I'm being told this amount of acid consumption is normal for some pools, and I'm aware that SWGs increase pH. However, given that salt water pools are apparently "low maintenance" it seems excessive that not adding acid every day will result in water that is not within limits. I'm also being told to increase TA to reduce the pH fluctuations.

    I notice that what I'm being told does not match with the Water Balance for SWGs page. I've also been assuming that less CYA is better because it is toxic in higher concentrations.

    Time to challenge all my assumptions and get some advice.

    Latest readings:

    FC: 2.6
    pH: 7.5
    TA: 130
    CH: 200
    CYA: 35
    Cl: 4300 (SWG says 3750 is optimum)

    Water temperature is 29 degC (it's been quite hot lately). The SWG is set to 30%.

    Pool shop recommendation [TFP recommendations]:

    FC: 2-4 [3-5]
    pH: 7.2-7.6 [7.5-7.8]
    TA: 100-140 [70-90]
    CH: 150-400 [300]
    CYA: 30-70 [70-80]

    Proposed Actions:

    Based on the TFP SWG recommendations I am contemplating:

    Keep the pH under 7.8 rather than 7.6?
    Reduce my TA from 130 to 90?
    Increase the CYA from 35 to 70?
    Increase the CH from 200 to 300?

    Does that sound like the right approach?

    Thanks for your help!

    28k litre in ground, concrete, Quartzon finish, 5yrs old.
    1.5 kW pump, Hayward 24" sand filter, Poolpower RP23 SWG.
    Solar heated, manually cleaned.

  2. Back To Top    #2
    JasonLion's Avatar
    Join Date
    May 2007
    Silver Spring, MD

    Re: Acid Consumption Seems High

    There are no significant health risks from CYA levels up to 100, or even well above that, as long as FC levels are adjusted to appropriate levels based on the CYA level. You will be much better off with CYA levels around 70 to 80.

    The key issue in the PH rise is the TA level. The higher the TA level the faster your PH will rise. Low CYA levels aggravate this effect by forcing the SWG to run longer, causing more total PH rise. If you follow our guidelines your acid usage will drop dramatically and everything will be much simpler to manage.

    The pool store recommendations you got aren't way off. You can get by with levels in the ranges they suggest, though various minor problems may ensue. But if you want your pool to be trouble free then try using our recommendations. The only change I would make to the numbers you wrote at the end would be to try lowering the TA below 90, but only go below 90 after you have gotten to the higher PH and CH levels.
    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

  3. Back To Top    #3

    Re: Acid Consumption Seems High

    This thread might help explain it:

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