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Thread: CYA FC confusion

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    CYA FC confusion

    Reading in Pool School, ABCs of Pool chemistry, "If you have a SWG or very high levels of direct sunlight, CYA is typically kept between 70 and 80." But when I look at the Chlorine/CYA chart 70 and up have an asterisk and say not recommended.

    My pool is in direct sunlight all day long so I'm thinking i want to be in the 70-80 range for CYA, does this sound right? Am I misreading the Chlorine/CYA chart?
    11,000 gal (21' round) AG
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    Re: CYA FC confusion

    That is correct if you're using a SWG.
    18*36*23 true "L" vinyl IG 29,000 gallons. SWG. TF-100 test kit.
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    Mod Squad tim5055's Avatar
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    Re: CYA FC confusion

    Generally the "full sun" folks are in Florida/Texas/Arizona. For PA, even in full sun I would start a little lower and work up if your FC loss during the day is too much. You can always add more, you gotta jump through hoops to get rid of it.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: CYA FC confusion

    With the SWG you should probably maintain the higher CYA. It allows you to not have to run your cell as much to maintain the needed chlorine in your pool. This allows a longer cell life.
    18*36*23 true "L" vinyl IG 29,000 gallons. SWG. TF-100 test kit.
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    Re: CYA FC confusion

    To clarify, I'm not using SWG. it was part of of piece i copied and pasted.

    I'm in PA, my pool is in direct sun all day long, and I'm trying to determine what CYA level to use. Still waiting for my Taylor K-2006 to come, but I've been using pucks for about 4 years or so, so I'm thinking it will be on the high side. Now I'm just reading everything and trying to understand.
    11,000 gal (21' round) AG
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    Re: CYA FC confusion

    I missed that. Tim is correct then you don't want to maintain the higher CYA. The SWG instruction difference is in my last post. Yes it requires a higher level of chlorine with higher CYA but it helps extend the life hours on the salt cell. That's why the different maintenance instructions for SWG that you see in pool
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    Mod Squad tim5055's Avatar
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    Re: CYA FC confusion

    Quote Originally Posted by 21 footer View Post
    To clarify, I'm not using SWG. it was part of of piece i copied and pasted.

    I'm in PA, my pool is in direct sun all day long, and I'm trying to determine what CYA level to use. Still waiting for my Taylor K-2006 to come, but I've been using pucks for about 4 years or so, so I'm thinking it will be on the high side. Now I'm just reading everything and trying to understand.
    if you test and are already on the high side and do not have an algae issue to deal with then you can stick with the higher CYA and jut chlorinate accordingly.

    Now, if your CYA is lower, say 50 stick there until it's proven you need extra CYA.
    TFP Moderator 39 X 18 23,000(ish) freeform gunite; built 2007ish; Pentair Triton II TR100 600lb Sand filter; 2 HP Pentair pump with 2.2 HP AO Smith single speed motor; 2 skimmers, 1 main drain, 4 returns w/waterfall, Stenner 45MHP2 3GPD running@ 60% - 15 gal Tank; heated by the sun CYA 200+ when I started - 50 now. Dolphin Supreme M5 Pool Cleaner. Hot Springs SX Spa, 285 gallon

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    Re: CYA FC confusion

    If you want a CYA number to shoot for, I'd start with 30-40 and see how it goes. Like was said, easy to add more, harder to lower!
    20k IG vinyl liner/Aqua Rite SWCG, T-15 cell/Hayward Pro Grid 6020 DE filter/Polaris 280 with booster pump/Hayward Superpump 1 hp/city water/pool installed March 2004

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    Re: CYA FC confusion

    I get a fail for thoroughly reading today.

    Definately post test test kit results when you get that. Your CYA could indeed be high under those conditions.

    What does the pool water look like?
    18*36*23 true "L" vinyl IG 29,000 gallons. SWG. TF-100 test kit.
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    Re: CYA FC confusion

    Even in normally "full-sun" TX, I manage CYA on the low side. As others have stated, it's much easier to add more than it is to get rid of it. Plus, I always leave a little room for vacations where I may have to use trichlor pucks temporarily.
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    Re: CYA FC confusion

    Hey 21 footer, I'm in Pittsburgh too (South Hills)! After getting pool stored for the last two years, I'm draining/refilling to head for a CYA of 50 (started at ~200). Pool is crystal clear, but need to maintain higher FC because of the high CYA.
    30,000 gal inground (20 ft. x 40 ft. w/ deep end), vinyl liner, Pentair Clear & Clear 420 cartridge filter, single speed 1.5 HP Pentair Whisperflow pump, heat pump, SunTouch controller

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    Re: CYA FC confusion

    Quote Originally Posted by scott39 View Post
    Hey 21 footer, I'm in Pittsburgh too (South Hills)! After getting pool stored for the last two years, I'm draining/refilling to head for a CYA of 50 (started at ~200). Pool is crystal clear, but need to maintain higher FC because of the high CYA.
    How much water did you have to drain to get down to 50, all of it?
    11,000 gal (21' round) AG
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    Mod Squad jblizzle's Avatar
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    Re: CYA FC confusion

    CYA will drop by the same % as the amount of water you drain. 200 to 50 would require replacing 75% of the water.
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    Re: CYA FC confusion

    CYA doesnt occur naturally in water. So draining the whole pool would result in a CYA of 0.
    Think in percentages.
    If your CYA is 100 and your target is 50, drain half
    If its 100 and your target is 40, drain 60%


    Quote Originally Posted by 21 footer View Post
    How much water did you have to drain to get down to 50, all of it?
    Divin Dave,
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    Re: CYA FC confusion

    finally got my test kit. here are my numbers

    FC 0
    CC 0
    TA 160
    PH 7.4
    CYA 70

    TA seems pretty high, i may test again, but right now i'm draining some water

    and ps, I'm crystal clear.
    Last edited by 21 footer; 05-26-2015 at 12:16 PM. Reason: forgot water condition
    11,000 gal (21' round) AG
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    Re: CYA FC confusion

    Thing that ticks me off is my ta was around 80 and pool store had me raise it
    11,000 gal (21' round) AG
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    Re: CYA FC confusion

    Now you need some chlorine
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    Re: CYA FC confusion

    Quote Originally Posted by 21 footer View Post
    Thing that ticks me off is my ta was around 80 and pool store had me raise it
    You can lower it once you have everything else in order. I can imagine your frustration though. Many of us listened to the pool store prior to coming to TFP.
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    Re: CYA FC confusion

    Quote Originally Posted by Azgirl71 View Post
    You can lower it once you have everything else in order. I can imagine your frustration though. Many of us listened to the pool store prior to coming to TFP.
    I returned 160.00 worth of their garbage today to them (phos out, algecide, shock) so at least I have that

    I figure if i can get the CYA to around 60 i can work with that for this year. Then I plan on replacing my skimmer next (or close of this season), and I'll have to do a big drain then.

    Putting about 6 inches of water back in now then will slam it.
    11,000 gal (21' round) AG
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    Mod Squad pooldv's Avatar
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    Re: CYA FC confusion

    Nice! Yes, CYA of 60 is manageable for sure. Good plan.
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