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Thread: SWG & CC

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    SWG & CC

    Okay, I'm making my way through Pool School. I found Water Balance for SWGs helpful.

    Note: I'll be purchasing the Hayward SwimPure.

    1. I don't fully understand CC. Is that the same as chloramine? Why is it important to test for it?
    2. In regards to a SWG, what should a good range (or upper limit most likely with the case of chloramine) be for CC? I assume it's okay to have it at or very near 0 ppm, right? At what point should I do something about the CC level? And what should I do - run the superchlorinator option?
    3. Do I pay attention to the Free Chlorine level and not the Total Chlorine level? Is the FC what I want to monitor to keep it in the 3-5 ppm range?
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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    Re: SWG & CC

    Quote Originally Posted by doglover78
    Okay, I'm making my way through Pool School. I found Water Balance for SWGs helpful.

    Note: I'll be purchasing the Hayward SwimPure.

    1. I don't fully understand CC. Is that the same as chloramine? Why is it important to test for it?
    2. In regards to a SWG, what should a good range (or upper limit most likely with the case of chloramine) be for CC? I assume it's okay to have it at or very near 0 ppm, right? At what point should I do something about the CC level? And what should I do - run the superchlorinator option?
    3. Do I pay attention to the Free Chlorine level and not the Total Chlorine level? Is the FC what I want to monitor to keep it in the 3-5 ppm range?
    1. CC is combined Chlorine. You want it at .5 or 0. Anything above that you need to shock.

    2. When it gets above .5 shock.

    3. With the TFT kit when checking chlorine you test one right after the other. But you FC is what you want to make sure is in range and CC is below .5.
    18x36 Grecian Vinyl; 8' Roman steps w/t 2 spa jets; cozy cove w/t 6 spa jets; 2 MD, 1 Skimmer, 3 returns; Hayward Ecostar, 30" Ranger sand filter; Hayward color logic 4.0 LED light; Hayward aqua logic; 2" PVC pipe 4 Jandy Valves

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    Re: SWG & CC

    Thank you kyle11!

    1. So CC should be 0.5 or less. Is it possible to get a result like 0.3 or are results in 0.5 increments?

    2. How can I shock a SWG? Can I use the built-in superchlorinator?

    3. Okay, so I pay attention to getting FC in range. And it looks like this forum recommends 3-5 ppm (judging by the Water Balance for SWGs page). I see others on the forum recommend higher, though.
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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    Re: SWG & CC

    You would only get intermediate results if you were to use a 25 ml water sample since every FAS-DPD drop would then be 0.2 instead of 0.5, but it's not necessary to be that precise. With the recommended 10 ml water sample, each FAS-DPD drop represents 0.5 ppm so you don't get anything in between.

    If you need to shock the pool, you would do so by adding chlorinating liquid or bleach. You don't want to run the SWG in superchlorinate mode since 1) it won't raise the FC fast enough and 2) it just wears out the SWG faster. Note that if you properly maintain your FC level relative to the CYA level as described in the Pool School, then you may never need to shock (except perhaps on spring opening if you don't maintain chlorine in the pool over the winter).

    Note that the recommendation is for the FC to be at least 5% of the CYA level. If you have your CYA at 80 ppm, that means a minimum FC of 4 ppm. See the Chlorine / CYA Chart for more details.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: SWG & CC

    Quote Originally Posted by chem geek
    You would only get intermediate results if you were to use a 25 ml water sample since every FAS-DPD drop would then be 0.2 instead of 0.5, but it's not necessary to be that precise. With the recommended 10 ml water sample, each FAS-DPD drop represents 0.5 ppm so you don't get anything in between.

    If you need to shock the pool, you would do so by adding chlorinating liquid or bleach. You don't want to run the SWG in superchlorinate mode since 1) it won't raise the FC fast enough and 2) it just wears out the SWG faster. Note that if you properly maintain your FC level relative to the CYA level as described in the Pool School, then you may never need to shock (except perhaps on spring opening if you don't maintain chlorine in the pool over the winter).

    Note that the recommendation is for the FC to be at least 5% of the CYA level. If you have your CYA at 80 ppm, that means a minimum FC of 4 ppm. See the Chlorine / CYA Chart for more details.
    Gotcha (except for the FAS-DPD test). Is 80 ppm what I should shoot for in regards to CYA (which would then mean going for 5 ppm of FC)? What about 70-75 ppm CYA and 4 ppm of FC?

    If it helps I'm in Florida.

    I really don't understand the FAS-DPD test...when you say each drop represents 0.5 ppm. Maybe I'll become more familiar once I have the kit and I'm doing it.
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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    Re: SWG & CC

    You want to start the season with CYA at 80, so it will still be around 60 to 70 by the end of the season. Don't worry about the slightly higher FC level target, you will use less total chlorine when CYA is higher even though you need to aim for a higher level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: SWG & CC

    Quote Originally Posted by JasonLion
    You want to start the season with CYA at 80, so it will still be around 60 to 70 by the end of the season. Don't worry about the slightly higher FC level target, you will use less total chlorine when CYA is higher even though you need to aim for a higher level.
    Okay, so I'll aim to get my CYA to 80 and it sounds like an FC level of 4-5? Even with an FC at that level I'll be using/producing less chlorine because the CYA will be holding more of it?

    What FC level do you recommend for Florida and a CYA of 80 (in a SWG)?
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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    Re: SWG & CC

    Why don't you start with 5 ppm FC and 80 ppm CYA and see how things go. If everything is in good shape and the SWG is able to keep up then you can try slightly lowering the target FC, but just keep in mind that you want the minimum to be 4 ppm FC so that means the FC when the SWG starts up again in the morning. If it were 4 ppm during the day but then lost a little at night when the SWG was off, you could go below the minimum.

    Does your pool have a screen shade that cuts down the amount of light on the pool? We're assuming that you're getting direct sunlight. If you've got a shade, you may find that your chlorine loss is a lot lower in which case the higher CYA wouldn't be as necessary though it will extend the life of your SWG cell since it's % on-time will be lower.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: SWG & CC

    My pool is screened in but does not have a screen shade. It does get a good amount of Florida sun.
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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    Water balance: Hayward vs TFP

    I'm continuing to go through pool school and found the Water Balance for SWGs page. I know it's stated in there that the recommendations on TFP may slightly differ with manufacturer recommendations. I'm just curious to know why. Is this through trial and error by TFP members? Are the ranges on Water Balance for SWGs applicable to all SWG systems?

    Here are Hayward's recommended ranges: http://www.hayward-pool.com/pdf/lite...us_TriFold.pdf

    What do you think I should start my salt level out on? Hayward's range is 2700-3400 ppm. I know you recommend 200-400 above the recommended optimal level. I guess the optimal level would be between 2700 and 3400 so 3000-3100, so maybe around 3300?
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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    Re: SWG & CC

    As much as possible, please keep your posts under one thread, even if seemingly unrelated. It helps for continuity.

    My answer may seem abrupt but be careful not to over think the salt level. If your SWG thinks it has enough salt, it will produce chlorine just fine.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: SWG & CC

    Sorry about that. I should just form one massive thread and title it "SWG - newbie and confused"
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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    Re: SWG & CC

    "SWG - newbie and confused"
    BUT...making VERY rapid progress!!

    Everyone one of us on this forum was a complete newbie at one point so you are in good company.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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    Re: Water balance: Hayward vs TFP

    Quote Originally Posted by doglover78
    I'm continuing to go through pool school and found the Water Balance for SWGs page. I know it's stated in there that the recommendations on TFP may slightly differ with manufacturer recommendations. I'm just curious to know why. Is this through trial and error by TFP members? Are the ranges on Water Balance for SWGs applicable to all SWG systems?
    Our recommendations are applicable to all SWG systems.

    Hayward, and most other SWG manufacturers, recommend 1-3 ppm FC with 60-80 ppm CYA, but except for the combination of 3 ppm FC with 60 ppm CYA the manufacturer recommendation is much more likely to have algae grow faster than chlorine can kill it. These manufacturers do not know nor understand the science behind the chlorine/CYA relationship even though it was definitively determined in 1974 in this paper. Specifying separate FC and CYA ranges rather than a target FC/CYA ratio (that we conveniently put into table form in the Chlorine / CYA Chart) is ridiculous and completely inconsistent with the chemistry, yet is what virtually everyone in the pool/spa industry recommends.

    The TFP recommendations for the FC/CYA ratios originally came from the experience of Ben Powell at The PoolForum and PoolSolutions who observed this relationship and looked at a paper written by a chemist, John Wojtowicz, to better understand the chemistry. I came along later and dove into the chemistry in more detail and made the ranges more consistent with the chemistry. That was the basis for the manually dosed non-SWG pool recommendations at TFP.

    For SWG pools, we found that such pools didn't seem to need quite as high an FC target as non-SWG pools so we lowered that recommendation. We do not know why for sure -- it might be partly due to the higher salt level or might be due to the superchlorination in the SWG cell (though that would not affect algae growing on surfaces that doesn't get circulated), or might be due to the more consistent dosing (though automatic dosing systems such as peristaltic pumps and The Liquidator tend to require the non-SWG FC/CYA levels).

    As for the Alkalinity level, Hayward and most other manufacturers propose 80-120 ppm, but we found that this results in too much pH rise due to carbon dioxide outgassing. Total Alkalinity (TA) is mostly a measure of how over-carbonated pool water is with respect to air. The increased aeration from the hydrogen gas bubbles from an SWG force more of this carbon dioxide out of the water faster and having a lower TA target of 60-80 ppm helps reduce this effect. Keeping the pH higher also helps as shown in this chart and is why we recommend a target of 7.5-7.8 instead of the Hayward range of 7.2-7.6.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: SWG & CC

    Wow, thanks Chem Geek!!!
    15K gal, IG plaster, screened, Marathon Electric 1 HP single speed pump, Hayward c-900 cartridge, Hayward SwimPure 40K SWG

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