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Thread: Understanding FC Loss

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    Sidecarist's Avatar
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    Understanding FC Loss

    Hello all. I have sorted out most of my issues and been through the SLAM process with your help only to discover that my SWG is toast so now I am using Bleach to maintain my FC.

    my current complete test results are below:
    FC 8
    CC 0
    PH 7.6
    TA 70
    CH 270
    CYA 75-80
    SALT 4000

    My CYA is high because I thought I'd be using the SWG. I'll accept the higher FC level I need to maintain because of that.

    My question is that I'm loosing an average of 5.5ppm FC every day with very low swimmer load my wife and myself every evening for a cool down of half hour to an hour in length. My CC is regularly at 0.5 or 0.0. I have done an OCLT 3 times where I start with an FC of 10-12 and its less than 1ppm loss three days in a row. Given that it has been hot and sunny 90-95degF and the pool gets a good solid 8 hours of direct sun every day is this 5.5ppm FC loss in an acceptable range given my high CYA of 75-80? (This is my first pool and i just don't have the experience to rely on for these answers)

    Water temp averages 85degF.

    Thanks!

    Bob
    12,000gal Fiberglass In Ground, Pentair 1hp single speed pump, and Pentair 100sq/ft single cartridge filter. Intellichlor IC-40 SWG, Roof mounted 400ft solar heat loop, Zodiac MX8 Elite cleaner w/leaf canister
    Taylor K-2006-C, Speed Stir, Taylor K-1766 salt test

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    Texas Splash's Avatar
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    Re: Understanding FC Loss

    Hi Bob! If I did the math correctly on the calculator, losing 5.5FC on your 11K pool equates to about 90 oz of 8.25% bleach (about 3/4 gallon) each day correct? Ideally we might like to see a little less FC usage, but your CYA should help. Keep in mind that if we round-up your CYA to 80 to be safe, then you are actually below your FC target level of 9 since you are no longer using your SWG. So watch that very closely so it doesn't get too low in this heat and allow cloudiness and algae to set-in.

    We'll only lose FC to the sun or algae. I know you did the OCLT 3Xs, but perhaps you might consider doing it with a higher FC mainly because your CYA is so high from the old SWG. If you take the FC up closer to the 30-range (29-31), you may be surprised the next morning. Just something to consider since you can't really go any higher on CYA.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
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    Sidecarist's Avatar
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    Re: Understanding FC Loss

    Yes roughly 3/4 gallon of 8.25% a day.

    The water looks and feels very good and we are happy with the pool overall, I'm just trying to understand what is "normal"

    I can try the OCLT at a higher level I just picked up 6 gal of bleach today so I have enough on hand. I'll get it bumped up there tonight and post results in the morning.

    The only other thing I can think of that may have an effect is that we are at 2500ft above sea level and I have noticed that "up here" paint fades more quickly etc so the Sun does have a somewhat greater effect.

    Thanks
    12,000gal Fiberglass In Ground, Pentair 1hp single speed pump, and Pentair 100sq/ft single cartridge filter. Intellichlor IC-40 SWG, Roof mounted 400ft solar heat loop, Zodiac MX8 Elite cleaner w/leaf canister
    Taylor K-2006-C, Speed Stir, Taylor K-1766 salt test

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    Texas Splash's Avatar
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    Re: Understanding FC Loss

    Interesting. Well, I'll be curious to see how the test turns-out tomorrow morning. Good luck, and have a nice evening.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Texas Splash's Avatar
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    Re: Understanding FC Loss

    Curious how your OLCT results turned-out?
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Sidecarist's Avatar
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    Re: Understanding FC Loss

    Sorry for not posting. I got called away for work.

    OCLT results started 8PM with FC 32, CC 0, 7AM FC 29, CC 0.5

    Roughly a 10% loss, definitely more than 1, so I'll keep it elevated and consider this the beginning of a SLAM. The little buggers crept up on me... Hopefully it shouldn't take long to get thing back under control.

    Bob
    12,000gal Fiberglass In Ground, Pentair 1hp single speed pump, and Pentair 100sq/ft single cartridge filter. Intellichlor IC-40 SWG, Roof mounted 400ft solar heat loop, Zodiac MX8 Elite cleaner w/leaf canister
    Taylor K-2006-C, Speed Stir, Taylor K-1766 salt test

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    Texas Splash's Avatar
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    Re: Understanding FC Loss

    Thanks for the update Bob! Perhaps that was the key (OCLT). Hope it clears up fast with that high FC level. Have a nice weekend.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

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    Sidecarist's Avatar
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    Re: Understanding FC Loss

    I'm still learning how to recognize trouble. It looks like I caught it early this time.

    Thanks

    Bob
    12,000gal Fiberglass In Ground, Pentair 1hp single speed pump, and Pentair 100sq/ft single cartridge filter. Intellichlor IC-40 SWG, Roof mounted 400ft solar heat loop, Zodiac MX8 Elite cleaner w/leaf canister
    Taylor K-2006-C, Speed Stir, Taylor K-1766 salt test

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