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Thread: Finding the CYA sweet spot

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    Join Date
    May 2012
    Location
    Redding, CA
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    24

    Finding the CYA sweet spot

    Looking for advice on CYA level...

    CYA 30
    pH 7.5
    TA 130
    CH 260
    CC < 0.5
    OCLT 1 ppm

    I seem to be using a lot of bleach, FC to about 6 after dark, and by 3 or 4 pm next day FC is about 1 (Min should be 2 with my current CYA). Adding 5 ppm is nearly a gallon (112 oz) of 12.5%, which costs me about $4.50/day (more than I expected to be spending on bleach). Actually, many days I'm adding 1-2 ppm of bleach in the afternoon, to avoid dropping below the min, so my cost is more than calculated above.

    I know I'm fighting a lot of sun... Redding, CA (far Northern CA), full sun all day, and it's been 95-105F this past week or two. I'm concerned if I bump up to CYA 40 or 50, I'll need higher FC levels that just drop faster in full sun, i.e. I think I read somewhere here FC drops essentially with half-life kinetics. Will the extra CYA lengthen the half-life of FC? If so, I it would make sense to increase my CYA.

    Thanks!

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    Smykowski's Avatar
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    Re: Finding the CYA sweet spot

    Yes, I'd bump it to 50. There seems to be a tipping point on CYA where all of a sudden the FC drop slows down drastically once your CYA threshold is crossed.
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
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    Whatrymes's Avatar
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    Re: Finding the CYA sweet spot

    Quote Originally Posted by Smykowski View Post
    Yes, I'd bump it to 50. There seems to be a tipping point on CYA where all of a sudden the FC drop slows down drastically once your CYA threshold is crossed.
    That's been my experience exactly. I was hoping to keep my CYA at 30 ppm but was losing 'bout 4 ppm of chlorine a day. After raising the level to 40, and after a few days, suddenly my chlorine loss slowed down significantly. We are now losing 1 - 2 ppm a day.
    15 X 30 X 3.6 Ester williams AGP
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  4. Back To Top    #4

    Join Date
    May 2012
    Location
    Redding, CA
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    24

    Re: Finding the CYA sweet spot

    Thanks for the quick replies! I just added CYA to the sock, aiming for 40 ppm. I'll check it in about a week, and see how it goes, then bump up to 50 if I'm still losing too much FC.


    22,500 gal, IG plaster
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    24000 Gal in ground plaster pool. Pentair FNS 35 DE grid filter. 3/4 HP single speed pump.

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    Mod Squad Bama Rambler's Avatar
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    Re: Finding the CYA sweet spot

    I run mine at about 50ppm or a little higher.

    The first thing to do is run a OCLT to make absolutely sure it's not organics eating the chlorine and then start raising the CYA until you're losing about 2ppm per day (24hrs).
    Dave J. TFP Moderator
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