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Thread: Balancing CYA - need feedback

  1. Back To Top    #1

    Join Date
    Mar 2007
    Houston, TX

    Balancing CYA - need feedback

    So it appears my PB put way too much CYA in my new pool. Multiple tests are coming back at 110. I have been keeping my FC north of 5ppm but would prefer not to have to leave it up there. I need some confirmation on my thought process on lowering my CYA.

    Its currently at 110 and I want it to be at 75 as recommended by my SWCG. 75/110=.68, 1-.68 leaves .32 or 32% of fresh water required to lower my CYA down to 75. Is my thinking even remotely correct?

  2. Back To Top    #2
    Mod Squad JohnT's Avatar
    Join Date
    Apr 2007
    SW Indiana
    Yes. Usually easier and safer for the pool to drop it in increments of 10% or so. First cycle will drop CYA 10% or 11ppm. Second cycle will drop CYA 10% or 9.8ppm. Third will drop it 10% or 8.9 ppm. That will get you to about 80.
    TFP Moderator
    20K Gallon 20X36 Vinyl Inground
    Hayward S244T Sand Filter with 1HP Whisperflo Pump. Liquidator C-201 and Solar Heat

  3. Back To Top    #3

    In the Industry

    Join Date
    Mar 2007
    Knippa, Texas
    Use the "sheet method"; cover the pool with a plastic dropcloth and start draining while running fresh water from the hose on top of the sheet. The sheet keeps the fresh water from mixing (much) with the old.

    That way you don't significantly lower the water level while replacing your water.

    My pool: INDOOR 13x27 rectangular fiberglass, built ~2001, BBB, TA-60 sand filter, Hayward two speed pump (1 hp/0.33 hp), 3/4 hp booster pump for solar heater
    Taylor K-2006 test

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