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Thread: Acid usage and CYA level in SWG pool

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    simonmoll's Avatar
    Join Date
    Feb 2014

    Acid usage and CYA level in SWG pool

    I recently installed a Hayward SWG.
    It recommends CYA level of 30-50.
    I see that the Pool School recommends a much higher CYA of 70-80.

    I have used a five gallon drum of acid in 6 weeks which is almost a pint a day.
    I have now gone with TFP advice and ..

    Upped the CYA.
    Got TA in recommended range.
    Will increase PH from 7.2/3 to 7.6 tomorrow I hope!.

    Can anyone give me an idea of how much acid I should be using?
    11,750 gall. concrete, in ground pool in Barbados. Shallow (max depth 4'6"). New (May 2016) Hayward variable speed pump and SWG and (make?) PH controller. Hayward Star Clear filter (50 sq ft). History of algae but not since joining TFP! Surrounded by coconut trees and other palms. Serious white fly infestation of palms continues.

  2. Back To Top    #2

    Join Date
    Jul 2014
    Hope Mills, NC

    Re: Acid usage and CYA level in SWG pool

    If you can balance your TA and pH, you will use less muratic acid.

    I still have the same gallon from last fall.
    16 x 32 17500 gallons
    Vinyl in-ground
    Hayward 250# Sand Filter
    1 HP Pump
    Hayward SWG

  3. Back To Top    #3
    needsajet's Avatar
    Join Date
    Jan 2016
    Sydney, NSW, Australia

    Re: Acid usage and CYA level in SWG pool

    At the end of my southern hemisphere swim season, I was using about 34 ounces (1 litre) per week and my plaster was more mature than yours is now. The upward creep of pH is coming from several things related to aeration - swimming, splashing, weather, water circulating, bubbles from the SWC coming up from the returns). It's also coming from your plaster as it continues to cure, and this part will slow down.

    Keeping TA down (60/70 or even a bit less) will help reduce the speed of pH increase, making additions less frequent.

    After the plaster is fully cured, you will very likely find a sweet spot for pH and TA where your acid additions are much less than they are now. When my plaster was young, I was using a lot more acid than I was by the end of the swimming season. At the same age as yours, I was using around 2 litres a week. I also learned to keep my pH at the upper end of the recommended range, which seemed to require less acid.
    12k IG salt; glass beads in plaster; K-2006C, K-1766, CCL, and Aussie 4in1 (HTH); Pentair Eco800 1.2HP VS; Zodiac SWC 1.3 lb/day (25 g/hr); 25" filter recycled glass; OKU solar panels; 1/2 HP solar pump; Rebel (Warrior) pool cleaner; FlowViz; prior pool AG 10k | Read Before Posting to get the best possible advice | ... and this helped me a lot!: TFPC for Beginners

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