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Thread: Downside of a non-SW pool with 70 CYA

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    Downside of a non-SW pool with 70 CYA

    Just trying to figure out what the downside is to having CYA at 70 in our pool. Deciding if I should drain out some water.

    Thanks all!
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    Richard320's Avatar
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    Re: Downside of a non-SW pool with 70 CYA

    I've maintained a pool with 3X your CYA level, but I don't recommend it if it is at all avoidable. You're going to have to depend on the FAS-DPD tester because FC should never drop below 5 with 70 CYA, and your target will be more like 8. That color matching tester is useless right now - it maxes out at 5. All it will be able to tell you is if you're too low, but it can't even tell you by how much. If you do need to perform the shock process because FC dipped too low for too long, you'll end up buying chlorine by the barrel, not the jug!

    You can work on lowering CYA by running irrigation water through the pool. Drain off a few inches and use it to water the lawn, then refill the pool with what you would have used on the lawn.
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    Re: Downside of a non-SW pool with 70 CYA

    Gotcha. Great stuff. I'll consider slowly draining some.

    Yeah, we have the k-2006 so I hope we are getting the hang of being on top of our levels. But with how high the CYA is, I don't want to have to go thru a ton of chlorine. We can't handle the expense.

    I guess maybe I should have asked if there is a benefit to having high CYA too. Other than the Chlorine going away slower, I would assume.

    Thoughts?
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    Isaac-1's Avatar
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    Re: Downside of a non-SW pool with 70 CYA

    The problem with a CYA level of 70 is that if algae ever gets established in your pool due to your level of FC dropping below minimum then it will be almost impossible to defeat without substantial water replacement prior to shocking. A low FC event / need to shock can be caused by equipment failure, storm debris, or any number of other unpleasant events. So it is not so much a matter of if it will happen, but when.
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    Re: Downside of a non-SW pool with 70 CYA

    I had my CYA at 30 last year (full sun pool) and had a hard time maintaining my chlorine level... I'd forget to add bleach one night, or would add the wrong amount, or it would all burn off in one day, or whatever - it was especially since I didn't have my k-2006 yet. I purposely pushed my CYA to 50 this year since my exposure is full sun, and have had a much easier time with it. For my size pool, I need 1 jug of 121 oz 8.25% bleach each night to maintain 4-6ppm range. It goes to 6ppm with the addition of bleach at night, and drifts down about 2ppm within 24 hours. That puts my bleach cost right about $3/day for my good-sized pool.

    I am a newbie, but think if I have less CYA in the pool, I may lose MORE than 2ppm per day, and thus need more than one jug per day to maintain my FC level, but I'm not sure exactly. Isn't the CYA a sort of "fixative" for the FC and if there was less CYA, you get less "fixative" action? Would love a chemically-inclined person to answer that!

    As I get more and more comfortable with having a sparkling clear pool, I'm experimenting with things. About a week ago, I reduced my pump time from 19 hours per day down to 8 hours a day split into two sessions, and so far holding clear. I may let the CYA drift down and see what it does to my FC levels, but I don't want to change more than one variable at a time, so am going to get the pump timing nailed down first.

    I think with a higher CYA level means do not let it get out of hand - because a high CYA means you will pay in costs when it comes time to shock. If you never need to shock because you maintain good levels as a matter of course, it's not that big of a deal. My two cents, anyway.

    Good luck to you!
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    Administrator Leebo's Avatar
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    Re: Downside of a non-SW pool with 70 CYA

    Quote Originally Posted by Isaac-1
    The problem with a CYA level of 70 is that if algae ever gets established in your pool due to your level of FC dropping below minimum then it will be almost impossible to defeat without substantial water replacement prior to shocking. A low FC event / need to shock can be caused by equipment failure, storm debris, or any number of other unpleasant events. So it is not so much a matter of if it will happen, but when.
    I tend to somewhat disagree with this statement. With a CYA level of 70 your shock level will be 20FC....while at a CYA level of 40 it's down to 15FC. In a 10K gallon pool you're only talking about a difference of just over 1/2 a gallon. I do agree that lowering the CYA level would be best.....but I'm not sure if I'd drain any water on purpose at this point if the water is clear, and CC's are 0. Keep the FC between 5-10, let the kids splash out and enjoy the fresh water mother nature is giving you.....but I'd let it run it's course.

    But that's just my thinking......

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    Re: Downside of a non-SW pool with 70 CYA

    The problem with letting your FC get down to 2 ppm with a CYA of 50 is your are risking letting algae get established, the BARE MINIMUM you should ever let your FC down to is 3.7 ppm.

    Ike

    p.s. almost impossible might be an over statement, difficult, might have been a better choice of words at 70 ppm, almost impossible should probably be reserved for CYA levels over 80-90
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    Administrator Leebo's Avatar
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    Re: Downside of a non-SW pool with 70 CYA

    Quote Originally Posted by Isaac-1
    The problem with letting your FC get down to 2 ppm with a CYA of 50 is your are risking letting algae get established, the BARE MINIMUM you should ever let your FC down to is 3.7 ppm.

    Ike

    p.s. almost impossible might be an over statement, difficult, might have been a better choice of words at 70 ppm, almost impossible should probably be reserved for CYA levels over 80-90
    I agree, with 70CYA keep the FC raised at 5-10. Don't let it slip.

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    Re: Downside of a non-SW pool with 70 CYA

    Quote Originally Posted by Leebo
    Quote Originally Posted by Isaac-1
    I tend to somewhat disagree with this statement. With a CYA level of 70 your shock level will be 20FC....while at a CYA level of 40 it's down to 15FC. In a 10K gallon pool you're only talking about a difference of just over 1/2 a gallon.
    Let's go with 28 vs. 16.
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    Administrator Leebo's Avatar
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    Re: Downside of a non-SW pool with 70 CYA

    Then you're at 2gallons....a larger jump. I hate the difference between pool school and pool cal.

    Either way I'd let it ride and keep FC between 5-10.

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    Re: Downside of a non-SW pool with 70 CYA

    Well, I am not sure what to take from all of this??!!

    I think I may just let the CYA level decrease slowly over time and by water naturally splashing out, hoping it will decrease to around 50. But based on what I have been reading, that will take probably until next Summer, no?

    I just can't fly through chlorine but I will trust the wisdom of the board if thou sayest thusly.
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    Mod Squad woodyp's Avatar
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    Re: Downside of a non-SW pool with 70 CYA

    70 is managable for the rest of the summer--fair enough?
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    Re: Downside of a non-SW pool with 70 CYA

    Done and done. A million thanks. Enjoy the 4th!!
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    Administrator Leebo's Avatar
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    Re: Downside of a non-SW pool with 70 CYA

    Quote Originally Posted by ericjdaniels
    I think I may just let the CYA level decrease slowly over time and by water naturally splashing out, hoping it will decrease to around 50.
    A lot depends on the rain we've been having this year. Last year I maybe added a pound of CYA to up the levels to stay at 40, while this year I've been adding it left and right. The storms we've had in ohio added a TON of fresh water causing my levels to drop big time. It'll drop faster than you think I'm sure.

    70 or lower until next spring, then lower more if needed.

    Now go blow something up.

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    Re: Downside of a non-SW pool with 70 CYA

    Quote Originally Posted by woodyp
    70 is managable for the rest of the summer--fair enough?
    I concur, with one caveat: never, ever let your FC below he minimum. I did it this way last year, and my personal minimum was the PoolCalculator min + 1. Shocking at 70 would be difficult and expensive.
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