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Thread: question about CYA and SWG

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    ajackson's Avatar
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    question about CYA and SWG

    Ok.. with a SWG the CYA level needs to be higher. right now I am using liquid bleach. thinking of switching next spring

    what I dont undersand is the if you do not have a SWG the recomended levels for CYA are 70-80 but if you do not the CYA is only 30-50

    I am sitting right around 80 right now with the 1/2 drain and refill

    It is confusing to me that CYA doesnt go away without new water. and right now it is still so high.. So why with a SWG do I want it Higher? and I see lots of people on here are adding stabilizer with SWG.. So does that mean something in the Salt water messes with the CYA ??

    Please forgive my ignorance, but this part really confuses me.
    Thank you
    14500k inground, vinyl, built in 2007
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    Taylor K 2006

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    Mod Squad jblizzle's Avatar
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    Re: question about CYA and SWG

    The SWG adds FC slowly so the higher CYA better protects it from the sun.

    CYA only goes down if it its physically removed from the pool ... splash, backwash, etc.

    Salt has nothing to do with CYA.

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    Re: question about CYA and SWG

    Sometimes early in the season I get lazy and just leave my pump run all the time and then I tend to let my cya be lower. If my pump is running 24/7 I run my swg at night so as the chlorine doesn't get sunlight until morning comes.

    You can really do whatever you find works for you. I tend to go lower than suggested for swg, but higher than liquid chlorine and I find that works for me. Saves me a little $$ on cya that I can save for the next season... unless we have a lot of rain or backwash a lot one season.

    You will notice that the FC level is a bit lower for swg pools as well... I believe due to the higher cya level because the chlorine is a bit more protected. I've had mine fall to FC and been fine, but don't make it a habit! Hate to risk any algae... No fun!
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    ajackson's Avatar
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    Re: question about CYA and SWG

    Thanks for helping clear that up. I am still researching SWG for several weeks now.. I just dont know which one to pick..
    14500k inground, vinyl, built in 2007
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    Re: question about CYA and SWG

    My thoughts are that a SWG is generally producing chlorine more steadily then being added in once a day. I could be wrong, but that makes the most sense to me.
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    JesseWV's Avatar
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    Re: question about CYA and SWG

    The way I understand it is that you want more CYA to better protect the chlorine produced by the cell. This allows you to run the cell less thus prolonging it's life expectancy.

    The reason why the suggested FC level is lower for SWG pools is due to the fact that in the chamber where chlorine is produced the FC level is actually much higher for a short time until it re-enters the main volume of the pool and is dilluted again.

    I'm tempted to put a tap on my return to see how high it is.
    16k gal, 28'x3.5', Vinyl A/G, 1hp Pentair Dynamo 2-speed Pump, Hayward S160T Sand Filter, Intermatic HB800RCL Digital Timer, Intex 8110 SWG, TF-100 Test Kit, SpeedStir Author: Jesse's Graphical Pool Testing Log

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    Re: question about CYA and SWG

    That is a very interesting point about the amount of chlorine in the water when it goes through the cell. It seems almost like the water gets a little shock purification treatment as it passes through. Makes me like the swg even better.
    Built in October 2011, 16 x 26 x 20 L shaped vinyl IG steel wall pool, Hayward DE pro grid verticle filter 4800 pool, Hayward two speed superpump, 120,000 BTU Pentair Ultra Temp Heat Pump, Aqua Rite Salt system, 8' wide walk out steps, 2 skimmers, 4 returns, 2 main drains, 500 watt underwater light, intermatic mechanical timer

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    Re: question about CYA and SWG

    Quote Originally Posted by lkae4
    That is a very interesting point about the amount of chlorine in the water when it goes through the cell. It seems almost like the water gets a little shock purification treatment as it passes through. Makes me like the swg even better.
    There is something to this from what I have read. There is even more going on than just higher FC - one person described the conditions inside the SWG as "inhospitable" to living organisms or something like that.
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    Re: question about CYA and SWG

    I love "inhospitable to living organisms". I want no living organisms in my pool, except my grandchildren and family, of course.

    Interesting topic.
    Built in October 2011, 16 x 26 x 20 L shaped vinyl IG steel wall pool, Hayward DE pro grid verticle filter 4800 pool, Hayward two speed superpump, 120,000 BTU Pentair Ultra Temp Heat Pump, Aqua Rite Salt system, 8' wide walk out steps, 2 skimmers, 4 returns, 2 main drains, 500 watt underwater light, intermatic mechanical timer

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    Re: question about CYA and SWG

    Quote Originally Posted by lkae4
    I love "inhospitable to living organisms". I want no living organisms in my pool, except my grandchildren and family, of course.

    Interesting topic.

    I will second That... (except for the grandchildren part. my son is only 16 so I hope I have many, many many more years w/out LOL)
    14500k inground, vinyl, built in 2007
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    Re: question about CYA and SWG

    The ideal CYA level is a balancing act between pros and cons. Higher CYA means less chlorine used, but more trouble fighting algae. There are two main differences in the pros and cons when using a SWG. First, with a SWG there are several small differences that add up to a significantly lower chance of getting algae. That makes the "costs" of using higher CYA levels lower, since CYA around 70-80 only becomes really annoying when you are trying to get rid of algae. Second, the SWG is fairly expensive, and will last far longer at higher CYA levels. Those two changes shift the tradeoffs involved, and push the balance of pros and cons to a higher CYA level when using a SWG.
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    Re: question about CYA and SWG

    Fow what it is worth, my CYA is sitting at about 25 (low, I know), but I have had success there. I have my SWG output set to 25%, and run the pump for 8 hours (at 1200 rpm).

    It has worked for me all summer, but I will be upping the CYA when I open it next year. As this is the first year and I stumbled on something that has worked well, I didnt want to risk messing with it. Now that I am comfortable with what I am doing, I will be looking at optimizing it next year.
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