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Thread: pH levels and FC

  1. Back To Top    #1

    Join Date
    Jul 2010
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    Pardes Hanna, Israel
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    pH levels and FC

    Hi All,

    I have the following parameters established:

    1. Shading net over the entire pool area
    2. Opaque pool cover (at night and most of the time the pool is not in use)
    3. A working Liquidator
    4. 2 x 200gr Trichlor pucks already dissolved (approx. 15 ppm CYA according to the pool calculator)

    According to the (amazing) FC/CYA table, my target FC should be approx. 1.8 (with a suggested minimum of 2 my target is actually 2) which is where I manage to keep it thanks to the (excellent!) Liquidator, the CYA, and the shading net.
    My water is clear and clean

    I was wondering though - the comment at the bottom of the table states that FC is more effective at lower pH, and I remember that the higher the pH, the less effective FC is.
    My age old problem of rising pH seems to be a lot simpler to manage if I allow the pH to remain in the area of 7.5 instead of targeting 7.2.
    How does that affect the effectiveness of FC and should I have a different target than what the FC/CYA table suggests? (given that my pH is usually around 7.4-7.5)

    Come to think of it, are the values in the table given for a specific pH?
    If so, how do I adjust them given other pH values?

    Thanks,
    Yoav.
    15 KL (3300 imperial / 4000 US gallons) IG fiberglass pool, 61cm (24") Lacron sand filter, 3/4 HP Hayward pump

  2. Back To Top    #2
    Richard320's Avatar
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    Re: pH levels and FC

    It sounds like you have the pool under control and are now so bored you want to micromanage it!

    7.4-7.5 is perfect! That's the pH of tears, so you probably don't get stinging eyes from swimming under water. Just enjoy it.

    Yes, chlorine is marginally more effective at 7.2, not enough so you'd be able to tell. If pH was up into the 8s you'd need to address it. But you'd want to anyway, for skin and eyes and plaster! I think that footnote was there for the people who are shocking. You're not, so ignore it.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
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  3. Back To Top    #3
    Butterfly's Avatar
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    May 2007
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    Re: pH levels and FC

    Your pool sounds great

    Please post some pics of your pool, pool area and shading net!

    I am sure I'm not the only one who wants to see
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  4. Back To Top    #4

    Join Date
    Jul 2010
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    Pardes Hanna, Israel
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    Re: pH levels and FC

    Thanks guys - I get it :P
    In hopes I will keep this going all summer...

    The pics will have to wait a while as my pool area is a mess right now; I am working on replacing my suction side pipe and some of the tiles are out, pieces of grass hacked out, etc...

    On the up side, I did finish a big job (for me anyway) last week - we've been having issues with our very old and unsafe safety net for a long time, and I finally "got it covered"
    I learned how to make concrete and placed two new steel poles (which we can pull out when the season is over and replace with garden lighting poles). These poles allow me to put up the shading net and most importantly, my new safety pool cover securely over the pool.
    I can safely say that of all the things I took upon myself to build, repair, replace and what not, this project saved me a bundle of money.

    We let the kids "test" the safety cover a week ago before I placed the poles that hold it in place...
    http://www.youtube.com/watch?v=4I0tKA1lz7A

    I will post some pics as soon as its all tidied up.
    Yoav.
    15 KL (3300 imperial / 4000 US gallons) IG fiberglass pool, 61cm (24") Lacron sand filter, 3/4 HP Hayward pump

  5. Back To Top    #5
    JasonLion's Avatar
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    Silver Spring, MD
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    Re: pH levels and FC

    As soon as you have CYA in the water the active chlorine vs PH relationship changes completely and becomes far less significant. With CYA in the water you can more or less ignore the PH, other than keeping it generally in range, as it won't have much effect on the active chlorine level. There is more detail on this in the advanced chemistry topic.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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  6. Back To Top    #6

    Join Date
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    Pardes Hanna, Israel
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    Re: pH levels and FC

    Interesting... I didn't know that.
    Thanks!

    No micromanaging necessary after all
    15 KL (3300 imperial / 4000 US gallons) IG fiberglass pool, 61cm (24") Lacron sand filter, 3/4 HP Hayward pump

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