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Thread: Lowering CYA: How Long Can I wait to properly balance pool

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    Join Date
    Oct 2012
    Location
    Houston TX 77064
    Posts
    101

    Lowering CYA: How Long Can I wait to properly balance pool

    "is there a safe period of time that passes before corrosion of plaster likely?"

    Preparing pool for winter in Houston TX; this will be the start of BBB, too. CYA was at 160 last week, so emptied 1/2 the pool and brought it down to 80 this last weekend and intend to do another 1/2 to bring down to 40 next week.

    Before 1/2 empty:
    FC: 20
    CC: 0
    PH: 7.8
    TA: 110
    CA: 250
    CYA: 160

    After 1/2 empty, then refill:
    FC: 23 (shocked)
    CC: 0
    PH: 7.8
    TA: 240
    CA: 150
    CYA: 80

    After 1 gallon muriatic acid (two part introduction) (yesterday):
    FC: 21
    CC: 0
    PH: 7.0
    TA: 120
    CA: 150
    CYA: 80

    Temps:
    Out: 50 low, 75-80 high
    In: 70-72

    Calcite Saturation Index:
    -.7 to -.8
    13200 gal, IG, plaster, built 1985, replastered 2012, Mytilus MA-90C cartridge filter, 2716 Blue Line In-ground Pump and Motor (1 HP), (manual clean/brush/test with Taylor K-2006, TFP since 2012) in Northwest Houston TX

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    Mod Squad jblizzle's Avatar
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    May 2010
    Location
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    Re: Lowering CYA: How Long Can I wait to properly balance po

    Why did you add so much acid and lower the pH so far?
    That is a real problem as the pH test is not valid when the FC > 10ppm ... you should not test pH when the FC is high as it will read a false high level.

    What this means as your pH was probably fine and now it is WAY too low, but it is hard to know how low it is since the pH test is not going to be correct until the FC drops below 10ppm.

    You should add some borax to raise the pH so that it is reading up around at least 7.8 now (but not way above 8.2) and that should at least get the pH close to OK.
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
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  3. Back To Top    #3

    Join Date
    Oct 2012
    Location
    Houston TX 77064
    Posts
    101

    Re: Lowering CYA: How Long Can I wait to properly balance po

    I'm sorry, I didn't explain myself well with my original post. I am going to assume that the lack of responses means that my pool will survive my punishment until Friday, when I complete the task at hand. Thank you for your input.
    13200 gal, IG, plaster, built 1985, replastered 2012, Mytilus MA-90C cartridge filter, 2716 Blue Line In-ground Pump and Motor (1 HP), (manual clean/brush/test with Taylor K-2006, TFP since 2012) in Northwest Houston TX

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    Mod Squad jblizzle's Avatar
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    Re: Lowering CYA: How Long Can I wait to properly balance po

    So I guess my warning about the pH was not adamant enough?
    Jason, TFP Moderator
    18k IG pebblesheen pool, Hayward ProLogic P4 w/ T-15 SWG, Pentair 1HP 2-speed Superflo, Hayward 6020 DE filter
    500 sqft Heliocol solar panels, ThePoolCleaner, TF-100 test kit w/ SpeedStir
    Pool School + Test Kit + PoolMath = A TROUBLE FREE POOL
    If you found TFP helpful and we saved you money ... Become a TFP Supporter!

  5. Back To Top    #5

    Join Date
    Oct 2012
    Location
    Houston TX 77064
    Posts
    101

    Re: Lowering CYA: How Long Can I wait to properly balance po

    It was heeded.
    13200 gal, IG, plaster, built 1985, replastered 2012, Mytilus MA-90C cartridge filter, 2716 Blue Line In-ground Pump and Motor (1 HP), (manual clean/brush/test with Taylor K-2006, TFP since 2012) in Northwest Houston TX

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