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Thread: Managing high CYA levels?

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    JesseWV's Avatar
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    Managing high CYA levels?

    My CYA is currently 75-80ppm. I've read that at this level there can be problems fighting algae is a bloom occurs. I was wondering if there is anything I can do other than keeping FC above 6 to reduce this risk?

    Should I proactively add algaecide? My wife and step-son have blonde hair so I'm a little worried about it turning green from the copper.

    Also I was wondering why 80+ CYA is recommended for SWG set ups but not for bleach maintained pools? Is this just because it's more likely the SWG will keep the FC where it needs to be resulting in less risk of an algae bloom?
    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: Managing high CYA levels?

    The reason why high CYA levels make it tough to fight algae blooms is only because it takes so much more FC to wage the battle since so much of it is bound to CYA. You can still be effective, it just takes more FC and more persistence.

    You can add algaecide if you want that extra protection, but if you do, avoid the metal based ones and linear quat formulations. Polyquat 60 should be the only one that you should use. I think though that as long as youmaintain your FC at around 7 to 8, you should be fine.

    We recommend higher CYA levels in SWCG pools because it takes the SWCG cell longer to generate a given amount of FC than it would for us to add it by hand. The higher CYA gives the FC that extra protection since without it, the sun would burn the FC off faster than the cell could produce it, even with the cell set to 100% production. You want that cell to have an easy job because the higher the output is set for, the shorter the lifespan of the cell.

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    Re: Managing high CYA levels?

    Also I was wondering why 80+ CYA is recommended for SWG set ups
    minor clarification needed. SWG CYA level should be 60-80 but 80+ is excessive.

    Jesse,

    I can't remember if you are manually chlorinating but, if you are, you will find your pool much more manageable with CYA down around 40-50. Everything seems to work better, you will consume somewhat less chlorine, and you won't need to consider the expensive algaecide
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    Re: Managing high CYA levels?

    Based on Mark's experiments and the experiences of those who run high CYA pools, you use LESS chlorine at the higher CYA level in spite of the FC being proportionately higher. This seems to be due to a non-linear CYA shielding effect of the lower depths.

    Another way to keep the edge off of algae growth as insurance would be to use 50 ppm Borates in the pool. Unlike PolyQuat 60 that must be added weekly, the borates are a one-time dose except for making up for water dilution.
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    Re: Managing high CYA levels?

    Quote Originally Posted by duraleigh
    Also I was wondering why 80+ CYA is recommended for SWG set ups
    minor clarification needed. SWG CYA level should be 60-80 but 80+ is excessive.
    My apologies, I was going by memory.

    [quote:32cf4ppa]I can't remember if you are manually chlorinating but, if you are, you will find your pool much more manageable with CYA down around 40-50. Everything seems to work better, you will consume somewhat less chlorine, and you won't need to consider the expensive algaecide
    [/quote:32cf4ppa]
    I am manually chlorinating. With rainwater addition and refilling from backwashing I have managed to bring it down from 95 so it'll only be a matter of time before it comes down more.

    I am wondering how much more chlorine I'll use once I get down to 50. I was kind of enjoying losing only 1ppm per day.

    If I was a chemist I would try to come up with something similar to CYA with a higher ratio of hypochlorous acid for a given concentration of the compound. It would be great if this imaginary stabilizer chart was this:

    THIS CHART IS IMAGINARY - DO NOT USE IT - :
    (Except for in your dreams)

    Code:
    Imaginary     FC        FF        FC
    Stabilizer  Minimum   Target     Shock
    ---------  --------   -------    ------ 
       10	      0.3        0.5       1.8
       20	      0.6        1.0       3.3
       30	      0.9        1.4       4.9
       40         1.2        1.8       6.4
       50         1.5        2.3       7.9
       60         1.8        2.7       9.5
       70         2.0        3.2      11.0
       80         2.3        3.6      12.6
       90         2.6        4.1      14.1
      100         2.9        4.6      15.6
      120         3.1        5.4      18.7
    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: Managing high CYA levels?

    Quote Originally Posted by chem geek
    Another way to keep the edge off of algae growth as insurance would be to use 50 ppm Borates in the pool. Unlike PolyQuat 60 that must be added weekly, the borates are a one-time dose except for making up for water dilution.
    I will back this up. My chlorine demand has plummeted and my water is staying completely clear since going to borates. I believe I've had a background algae potential since buying my house which was contributing to my high chlorine usage. Since going to borates, my chlorine usage is scary low.
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    Re: Managing high CYA levels?

    We have a chart much like that one, but with real numbers, in Pool School, see here.
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    Re: Managing high CYA levels?

    and there's a link in that Pool School page to the one I originally made here that extends the CYA range higher (these being ultimately based on Ben Powell's original chart also linked to in my page).

    If chlorine usage is your most important factor, then you can operate at a higher CYA level but unless you use supplemental help (50 ppm borates, etc.) then you just have to be extra careful to keep your FC at the appropriate level relative to CYA at all times.
    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: Managing high CYA levels?

    Quote Originally Posted by chem geek
    and there's a link in that Pool School page to the one I originally made here that extends the CYA range higher (these being ultimately based on Ben Powell's original chart also linked to in my page).

    If chlorine usage is your most important factor, then you can operate at a higher CYA level but unless you use supplemental help (50 ppm borates, etc.) then you just have to be extra careful to keep your FC at the appropriate level relative to CYA at all times.
    I would love to add borates but I'm still on the fence about the safety of my children and pets with borates in the water. I've read two reports Chemgeek posted. One seems to indicate it's almost impossible to have problems and one seems to indicate that only a few tablespoons a day could start to create health problems.

    I have a dog and two cats. I've never seen the dog or cats drink out of the pool but that doesn't mean they don't. I have 3 children, 9, 8, and 2 years old. I worry mostly about my 2 year old. He definitely ends up swallowing at least a few oz of pool water every swimming session.

    I actually started adding borates until I read the PDF file: FQPA TRED for Boric Acid/Sodium Borate Salts
    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: Managing high CYA levels?

    Humans are safe at the borate levels we recommend, with a very large safety margin. Pets are also safe, but without the large safety margin. The concentration of borate in the pool water is very low. A pet would have to get all of their drinking water from the pool before there was even a remote chance of a barely detectable symptom.

    A few tablespoons of borax or boric acid powder is a major problem, a few tablespoons of pool water is no problem at all.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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