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Thread: CSI/CYA Level for SWG POOL

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    Join Date
    Aug 2014
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    Phoenix, Az
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    CSI/CYA Level for SWG POOL

    Morning, I am new to the forum I have some questions about water balance with Salt water pools.

    I have been playing with the Pool Math Guide and have been reading all the pool guide info supplied by the forum and I am kind of confused about a few things.

    Why is it recommended to keep a high CYA level on salt pools? (70-80) In the summers here in Phoenix the pool water will be 90 degrees on average and based on the Pool Math my CSI reading will become corrosive with a TA of 60 and a PH of 7.5 if the CYA level is at 70, in the winter no problem. It seems like with higher CYA levels I have a very small window to adjust PH. If I kept the CYA at 50 year round keeping my pool balanced seems to be a little simpler. I try my best to keep my PH at 7.8 and as low as 7.3 in the summer because the heat just eats through everything here plus, as you will see in my readings below calcium can become an issue very quickly if I don't stay on top of the PH and TA. How do you keep the CYA levels in check if they creep over the 80 mark? Im pretty sure all chlorines have some CYA in them.

    My Pool as it stands

    Dawn -

    FC 3
    CC 0
    PH 7.5
    TA 60
    CYA 30
    SALT 3600
    PHOS 1000 - - - I know its stupid high, and I am trying to get it down. I have no idea how it got so high, water is a month old.
    CH 390 - - - - PHX water is high in calcium. Nothing I can really do about it. Other than keep an eye on TA and PH weekly

    DUSK -

    FC .5
    CC 0
    PH 7.5 - rises to 8.0 by end of week. I am adding a half gallon of acid weekly to maintain
    TA 60
    CYA 30
    SALT 3600
    PHOS - 1000
    CH 390

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    Mod Squad JohnT's Avatar
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    Re: CSI/CYA Level for SWG POOL

    Welcome to TFP!

    Only a few chlorine forms have CYA in them. Dichlor and trichlor are stabilized and have CYA. Calcium hypochlorite doesn't have CYA, but it does have calcium, which you don't need.

    That leaves sodium hypochlorite or bleach. If you are going to chlorinate your pool, bleach or pool chlorine are the recommended sources.

    SWCG CYA are recommended by the manufacturers. The constant chlorine generation and the high levels the water experiences in the cell make up for the higher CYA and allow you to avoid problems that normally come from higher CYA levels.
    TFP Moderator
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    Re: CSI/CYA Level for SWG POOL

    So, what happens if I have to reduce TA by adding a higher than normal amount of acid? If the CYA is at 70 I can only reduce the PH so much before the water becomes too corrosive. And if the water Temp really plays that big of a roll in the sensitivity factor of adding acids how do I get around that? These questions are from me playing with the calculators. With my CYA at 30 I can reduce the PH to 7.2 safely, to reduce TA if needed or scaling control. If my CYA is at 70 then I can only reduce PH to 7.5 before it becomes too corrosive. What if a PH level of 7.5 isn't enough to get the adjustment I need? Does CYA help control TA and CH some how? Am I over thinking this?

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    Mod Squad JohnT's Avatar
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    Re: CSI/CYA Level for SWG POOL

    You are probably overthinking. Better to overthink and then adjust your thinking than to underthink and do something dumb! pH is only low for a short time during the TA reduction process, so it probably won't be an issue..
    TFP Moderator
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    Re: CSI/CYA Level for SWG POOL

    Haha, I figured once I read what I wrote. I am going to increase my CYA slowly to 50 and see what happens and how it effects my pool chemistry versus what it has been. Then push it to 70 if all goes well. Thanks for the help!
    25k Gal, Pebble Tec Inground
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    svenpup's Avatar
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    Re: CSI/CYA Level for SWG POOL

    Also, ignore phosphates. They are irrelevant if you maintain proper FC/CYA ratio.
    TFP Method Advanced Intermediate
    • 17,500 gallons - In Ground - Plaster - Hayward Swimclear 3020 Cartridge Filter - Sta-Rite Max-E-Glas Main Pump upgraded with A.O. Smith B2980 E-Plus New Centurion Two-Speed Motor - Polaris 280 Cleaner with Polaris PB4-60 Booster Pump - TightWatt2 Timer - Taylor K-2006 Test Kit - Pool Pilot Digital Nano SWCG

    Helpful Links: Pool School, BBB for Beginners, How to Shock (hint...it's a process not a product), Chlorine/CYA Chart, Jason's Pool Calculator

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