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Thread: My CYA keeps changing

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    My CYA keeps changing

    So last Sunday the pool store said my CYA was 60. Friday I tested again I got around 55. The following day Saturday I took it to the pool store and they said it was 40. Previous tests at the pool store have also differed one was 30 then 50 then 40. I will test it again myself and post my results. I thought my CYA would not change that much once in the pool. I am using tablets but thought those would only raise CYA not cause it to fluctuate. I know splash out can affect CYA what about bather load?

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    Mod Squad JohnT's Avatar
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    Re: My CYA keeps changing

    The level won't change. Most likely it's poor testing at the store.
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    Mod Squad woodyp's Avatar
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    Re: My CYA keeps changing

    Pumping out rain water, backwashing, and adding water from evaporation will all change it.
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    Richard320's Avatar
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    Re: My CYA keeps changing

    The difference is who is testing it. It's a subjective test, really, so no two people will ever read exactly the same, even using the same sample, the same view tube, and the same light. Now add in different tests and different people and different light, and you have confusion.

    A man with two watches never knows exactly what time it is, a man with two compasses never knows exactly where North is, and a man letting a pool store test his water never knows what his pool water really contains.
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    Re: My CYA keeps changing

    So I tested yesterday and got about 55 60 I'm taking the pucks out of the chlorine feeder and going with liquid. Does the fact that I live in southern california and my pool is in direct sunlight all day mean I need a higher CYA level or does that not matter?

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    Re: My CYA keeps changing

    If you don't have a salt water pool, I wouldn't go any higher on your CYA
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    Re: My CYA keeps changing

    Just a question to clarify what Woodyp said above: evaporation will result in a loss of CYA? Meaning unlike salt (which simply concentrates in the remaining water), CYA does not concentrate but rather evaporates along with the water?

    I ask because I just checked my CYA after several weeks of no cover on the pool, and maybe three to four inches of overall evaporation & replacement (not all at once). CYA seems to have dropped from 80 to 65 (I say "seems" because I always have a bit of trouble with that test).

    Thanks!
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    Re: My CYA keeps changing

    Quote Originally Posted by Steverino
    Just a question to clarify what Woodyp said above: evaporation will result in a loss of CYA? Meaning unlike salt (which simply concentrates in the remaining water), CYA does not concentrate but rather evaporates along with the water?

    I ask because I just checked my CYA after several weeks of no cover on the pool, and maybe three to four inches of overall evaporation & replacement (not all at once). CYA seems to have dropped from 80 to 65 (I say "seems" because I always have a bit of trouble with that test).

    Thanks!
    CYA does not evaporate.

    I think woodyp was just mentioning that rain water can reduce CYA concentration by increasing the water level (higher than normal) and if you pump off or drain water then you lose CYA. You also lose CYA if you pool overflows.
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    Re: My CYA keeps changing

    Thanks linen. 'Course now I'm left wondering where my CYA went since I've not backwashed, pumped off, or overflowed any water. Only loss has been due to evap. and then I've refilled back to the "normal" level. Hmmmmm...
    29,000 gal. vinyl in-ground mountain lake (freeform); Hayward DE filter, 2 skimmers, AutoPilot SWG, 2 - 4 X 20 Fafco Solar Bears with Goldline control, Aquabot, LoopLoc winter cover, Pool installed March 2009...

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    Re: My CYA keeps changing

    The accuracy of the CYA test is +/- 15ppm
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    Re: My CYA keeps changing

    Duh. I'd forgotten about the accuracy range. I wish somebody'd build a better mousetrap for that one.

    Thanks, though.
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    Re: My CYA keeps changing

    Anytime. I like to perform the test a few times by pouring the tube back into the mixing bottle and just repeat the test. I usually take the avg of 3 tests
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    Mod Squad Bama Rambler's Avatar
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    Re: My CYA keeps changing

    Quote Originally Posted by dmanb2b
    Anytime. I like to perform the test a few times by pouring the tube back into the mixing bottle and just repeat the test. I usually take the avg of 3 tests
    That's what I do as well. You can pour it back and forth many times to get a concensus.
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    Re: My CYA keeps changing

    Agree, when I get the final reading, it's 'Do I see the dot or not see the dot, that is the question!!!'. Never thought of re-reading the same sample a couple of times, great idea. I also like to use TF's stirrer to mix the CYA sample. Mix for a minute, rest, then mix again, rest, pour in the TF squirt bottle, squirt into sample tube.
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    Re: My CYA keeps changing

    I too have been seeing a drop in CYA. We've had little or no rain here in the past couple of months, temps 95-110 and extreem sunshine. I lose at least 1/2" of water per day and have minimal splash-out. I've always believed that CYA dosen't evaporate but I've seen mine drop from 80ish to 40ish in the last few weeks. I've kept a good log since opening 4+ years ago and it's always been consistent until now.

    Donnie
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    Re: My CYA keeps changing

    Quote Originally Posted by arvil
    Agree, when I get the final reading, it's 'Do I see the dot or not see the dot, that is the question!!!'. Never thought of re-reading the same sample a couple of times, great idea. I also like to use TF's stirrer to mix the CYA sample. Mix for a minute, rest, then mix again, rest, pour in the TF squirt bottle, squirt into sample tube.
    The stirbar fits in the CYA bottle, and the CYA bottle fits on the speedstir. Just be sure to measure water and reagent before you drop the stirbar in.
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    Re: My CYA keeps changing

    Quote Originally Posted by DONNIE
    I too have been seeing a drop in CYA. We've had little or no rain here in the past couple of months, temps 95-110 and extreem sunshine. I lose at least 1/2" of water per day and have minimal splash-out. I've always believed that CYA dosen't evaporate but I've seen mine drop from 80ish to 40ish in the last few weeks. I've kept a good log since opening 4+ years ago and it's always been consistent until now.

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    Re: My CYA keeps changing

    positive. and if i did why doesen't the cya let the ta, salt and ch in on the secret. maybe its really a "cia" leak and my cya can't spell. i think it's the heat and intense sunshine combined with refills. there is no other explanation. btw...why do the pool stores etc stock so much cya? if you put it in and it stays there one would think that there wouldnt be so much demand for it.

    Just my $.02 you guys have a great day. off to the pool........

    Donnie
    8500 Gallon Fiberglass IG / Sta-Rite pump,cartridge filter & heater / PoolPilot Dig 220-36 SWG / Testing w/K2006

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    Re: My CYA keeps changing

    Quote Originally Posted by DONNIE
    positive. and if i did why doesen't the cya let the ta, salt and ch in on the secret. maybe its really a "cia" leak and my cya can't spell. i think it's the heat and intense sunshine combined with refills. there is no other explanation. btw...why do the pool stores etc stock so much cya? if you put it in and it stays there one would think that there wouldnt be so much demand for it.

    Just my $.02 you guys have a great day. off to the pool........

    Donnie
    it can get rain diluted, and splashed out. If the rain is causing over flow. Also back washed out. Or leaked as I mentioned.
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    Re: My CYA keeps changing

    Diluted? Thought that wasn't possible. There is no overflow, I have evaporation issues. Splash out is minimal, very minimal. 99% of the time it's my wife and I. I should be able to replace the spashout wit a teaspoon a day of CYA. All I can gather is runtime. I'm starting with 3 - 4 FC and running the pump 12 hours during the hottest, brightest part of the day. Maybe I need to run it 16 hours a day. I don't feel I should be having to use my new cell on level 2 at 37% (as of yesterday) already. I am positive about my testing and am positive I have no leak. i had a trace if CC's this morning. Im considering cleaning my filter and shocking to 18 CC tonight. What do you think?

    Donnie
    8500 Gallon Fiberglass IG / Sta-Rite pump,cartridge filter & heater / PoolPilot Dig 220-36 SWG / Testing w/K2006

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