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Thread: CYA loss

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    CYA loss

    Hi Guys, ti has been a while. Ever since taking over my own pool a year ago, things have been great, since starting over, doing two SLAMs etc.

    Anyway, even though it is winter, here is FL, the kids still use pool when temp over 72/73 degrees, so I have been testing CL, PH , adding acid to keep at 7.5 ph and scrubbing , every week.

    Anyway, I noticed yesterday that PH was at 7.0 - when all winter it has been rising to 8.0 and I have been ADDING acid.

    So, I decided to do more testing and got:

    CL - 3.5 (SWG set to 60% for 6 hours) which is high - I have been steadily increasing over last couple of months to maintain CL
    TA - 20
    Salt - 2600

    So, I added a bag of salt, 9lb of baking soda , and SALt now at 3100 and TA at 80. PH was up at 8.0 , so I just added some acid.


    I figured I might as well test the rest, as I was concerned on CL level , turns out , my CYA is at zero (well at least nothing shows on full test tube )

    So, mu question is, is it possible to drop CYA from 80 in August to zero now? Would this be due to rain?

    Can it actually be zero, or is there something wrong with the test chemicals?

    Pool Math table says I now need to add 192oz of liquid stabilizer - this seems a lot , right?

    I think this explains why my CL level has steadily dropped over winter from 8 to 3.

    On the up side, my high CH level of 460 is now down to 300 .

    Any thoughts on how to go about this CYA issue? OR should I just stick to the pool math table as always?

    thx
    12k SWG pool, free form. 1HP flotec pump, P90 Leslie's filter. Florida. Taylor 2006 test kit. I think plaster, waiting verification from here.

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    Texas Splash's Avatar
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    Re: CYA loss

    If I recall correctly, you folks have been receiving a lot of rain. Get enough of it and eventually it can begin to have a lowering effect on CYA and CH. Those are some big drops though. Keep in mind that the CYA tube really doesn't reflect anything below 20, so you may a little stabilizer in there but it's just not recording as anything. Still, you definitely need stabilizer, not only to protect the FC from the sun, but also to serve as a buffer for your skin, clothes, etc. So yes, trust the Poolmath calculator to get you back to your SWG's recommended 70-80 CYA range. And remember, you can use granular stabilizer which is about a 1/3 of the cost of the liquid stuff. The liquid does record faster as opposed to the granular that takes about a week or so to show-up, but it's up to you.

    As for the pH and TA ..... now that you've already adjusted the TA up to about 80, give it a few days to see if the pH stays constant of tries to climb again. It's okay to let the TA come down a bit (70, 60 etc), and that may help the pH stay down a bit better.
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    Re: CYA loss

    Ok,

    I have only ever used liquid stabilizer in the past, about 30 bucks a gallon. I will need nearly 2 gallons, so is there a recommended powder type that you just throw in the pool to dissolve? Or do you always have to do the whole sock thing? thx
    12k SWG pool, free form. 1HP flotec pump, P90 Leslie's filter. Florida. Taylor 2006 test kit. I think plaster, waiting verification from here.

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    Re: CYA loss

    I had a fresh fill from a new liner install last fall, I got the cya to 30.
    There were lots of rains, I probably have drained about 1 -2 feet of water which is a lot for my size pool and now my cya is zero as well.

    so ya the rain and drain to maintain water level will do that.

    I use the chlorox granules on amazon. 15 bucks for 4 lbs. I do the sock, but let it sit in the skimmer a few hours then run
    the pump and squeeze the now squishy granules until its all dissolved (takes about ten minutes to do) Then wait a week
    and re-test cya.

    looks like our pools are about the same volume.

    4lbs of that cya granules should get you to 35-45 cya
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    Texas Splash's Avatar
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    Re: CYA loss

    If you're not an Amazon Prime member for fast delivery, usually Wal-Mart, HD, or Lowes has granular Stabilizer in their pool section. Wal-Mart just re-packed theirs this year in a fatter, white jug with pink cap. About $16 or so I believe for 4 lbs.

    To increase CYA via granular stabilizer, simply place the required amount as calculated by the Poolmath calculator into a white sock and suspend it near a return jet. You can squeeze the sock occasionally to help it dissipate. Once dissolved, it may take about a week for the CYA readings to fully adjust.
    Pat (a.k.a. Texas Splash) ~ My Pool: Viking Fiberglass; 17,888 Gal; Waterway Supreme 2-sp/2-hp pump; Hayward Ctg filter; TF-100 w/ Speed Stir
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    Re: CYA loss

    You may just have low CYA. If you're at 20, it will look like zero.

    Take that into account when you add more. It's easy to add more later, hard to get rid of it. Although maybe not in your case with a lot of rain. Anyway, wait to retest the CYA until a week or so after it's all dissolved.
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    Re: CYA loss

    You can also put the sock with the powder CYA in a floater and let it dissolve that way.

    EDIT****I have to say I agree with the below posters. I never even thought of the floater by the side of the pool. BAD idea.

    Kim (still learning and am grateful for those who are willing to teach me!)
    TFP Moderator 33x52 round AG 25,600 gals Sand Filter 1.5hp Pump - 2 Speed, SLAM, Pool School, Recommended Levels, Recommended Chemicals, Pool Math, Chlorine/CYA Chart, TF-100 Test Kit

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    Re: CYA loss

    Thanks all. I am concerned that my FC is dropping too low and I do not want any algae growing - done all the SLAMs I ever hope to do ! lol

    I think I will just buy the liquid , I can get a couple of gallons as my Leslie Pool today for about 70 bucks, I think. I will need 5lb of solid, seems like a LOT of dissolving!

    Good advice on not assuming zero CYA. I will add one gallon , and re-measure.

    thx
    12k SWG pool, free form. 1HP flotec pump, P90 Leslie's filter. Florida. Taylor 2006 test kit. I think plaster, waiting verification from here.

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    Re: CYA loss

    Quote Originally Posted by kimkats View Post
    You can also put the sock with the powder CYA in a floater and let it dissolve that way.

    Kim
    I don't know that this will be bad or not, and I'm not sure we've proven it either way. One concern I have with doing it is will some fall out and possibly discolor a pool finish in some way? In practice it sounds like a great idea, and very convenient. If you mean while still in the sock that's a moot point, but I also wonder if it's possible for it to discolor a finish when it rests next to a wall, or over a bench, step, ledge etc. I think the answer is we just aren't sure. I may be overly cautious here, but it's an unknown we might not want to chance.
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    Re: CYA loss

    Do you think you have drained and replaced 75% of your pool water??

    Because if you do the math, to go from 80ppm CYA to even 20ppm CYA means that you would have needed to exchange 75% of your pool water with fresh water. And that's for a one-time exchange of water as opposed to multiple exchanges which would add a dilution factor to it and actually require more water than a one-time exchange. Based on your other numbers your salt showed a 16% drop and your CH showed a 35% drop.

    Something doesn't add up here and I would suggest you go slowly adding any new CYA to your pool. Testing error is always a possibility with the CYA test.
    Matt
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    Re: CYA loss

    CYA in a floater is probably not the best approach IF there is a way to do it better.......like a sock in the skimmer. Honestly,I'll bet both are OK but Patrick brings up a good point about the floater resting on a sidewall and doing some damage.

    My suggestion would be to do it if you need to but the sock in the skimmer is a safer approach.
    Dave S.
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    Re: CYA loss

    Quote Originally Posted by JoyfulNoise View Post
    Do you think you have drained and replaced 75% of your pool water??

    Because if you do the math, to go from 80ppm CYA to even 20ppm CYA means that you would have needed to exchange 75% of your pool water with fresh water. And that's for a one-time exchange of water as opposed to multiple exchanges which would add a dilution factor to it and actually require more water than a one-time exchange. Based on your other numbers your salt showed a 16% drop and your CH showed a 35% drop.

    Something doesn't add up here and I would suggest you go slowly adding any new CYA to your pool. Testing error is always a possibility with the CYA test.
    Good point. I have just re-tested and got:

    FC 5
    TA 80
    PH 7.8 (which I will leave as adding stabilizer today)
    CYA - 0

    CYA is totally clear, like pool water. I have done this test at least 30 times in the past, so pretty sure it is not test error. I even emptied out my small reagent and refilled from my pretty new 120z refill bottle.

    I will go buy liquid CYA now, and just add 1 gallon to start with and re-test.

    I have always hated the subjective and very inaccurate CYA test, but it is definitely crystal clear when testing right now.

    thx
    12k SWG pool, free form. 1HP flotec pump, P90 Leslie's filter. Florida. Taylor 2006 test kit. I think plaster, waiting verification from here.

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    Re: CYA loss

    There is bacteria that can consume CYA when water cools. It is relatively rare but we see it every winter.
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    Re: CYA loss

    I wouldn't add more than 10-15ppm at a time and retest. If you use liquid CYA, the results should be detectable within a few hours.


    Matt
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    Re: CYA loss

    Quote Originally Posted by pooldv View Post
    There is bacteria that can consume CYA when water cools. It is relatively rare but we see it every winter.
    Really?

    Does the FC not kill it ?

    I actually have a bacteria test kit, as the reason I took over my own pool was because my 4 year old has been doing major surgeries on her leg and swimming in pool is really good for her - but there are open wounds down to the bone.

    I will test for bacteria too.

    thx
    12k SWG pool, free form. 1HP flotec pump, P90 Leslie's filter. Florida. Taylor 2006 test kit. I think plaster, waiting verification from here.

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    Re: CYA loss

    Yes, it does, and we think most often that when bacteria causes the cya loss, it's during times of low-zero FC residual. We don't know if bacteria consumption of Cya is the sole explanation for Cya loss, but it's generally believed to be the leading cause of significant losses. Save of course, water replacement.

    As for testing for it I have no proof, but don't think you can confirm much with testing for it with the setup you have. No harm in looking at all, just not sure what you can quantify. I'd still be interested in what your tests show however.
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    Re: CYA loss

    Quote Originally Posted by simonoaks View Post
    Really?

    Does the FC not kill it ?

    I actually have a bacteria test kit, as the reason I took over my own pool was because my 4 year old has been doing major surgeries on her leg and swimming in pool is really good for her - but there are open wounds down to the bone.

    I will test for bacteria too.

    thx
    Several bacteria types can use CYA under anaerobic conditions as an energy source. However, if your water is missing the bacteria that converts ammonia to nitrite/nitrates, then you will get a huge ammonia mess on your hands.

    See this thread - Degradation of Cyanuric Acid (CYA))

    Matt


    Matt
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    Re: CYA loss

    So,

    I added 1 gallon of CYA yesterday and new results are:

    FC - 10 (had pump running all night though)
    TA - 120
    PH - way high - over 8 , so just added 2 cups of acid
    CYA - NOW 35.

    So, it seems, that I must have been at CYA 0 - as 1 gallon raised my pool to 35ppm - exactly what should have happened for a 10k gallon pool.

    What does that tell us ?

    I will add another gallon today to get it up to CYA 70

    Based on these findings, any steps I should take next ?

    thx
    12k SWG pool, free form. 1HP flotec pump, P90 Leslie's filter. Florida. Taylor 2006 test kit. I think plaster, waiting verification from here.

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    Re: CYA loss

    How many times have you had to drain excess rain fill?

    If it was many times, that would be likely the culprit....as it was on my 13k gallon pool.
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    Re: CYA loss

    I do not drain, when we get a storm and the pool over flows, it self-rights back to the same level. Same when during summer and I put the hose it and forget, it sometimes fills 3 inches higher than normal level , the self rights back again.

    I have read the info on CYA loss. My thoughts are, that probably mine is normal loss - all through the winter I have the SWG running, FC has never gone below 3ppm, and I test FC and PH 2 times per week.

    My mistake was that I did not test TA or CYA regularly, so only now noticed the problem.

    TA was down to 30 , PH was of course rising too quick between tests (the reason why I tested TA in first place)
    I guess I have lost 70ppm CYA since September, so taking into consideration Florida rain, and sunlight etc, that probably is not far off. I presume it cannot be bacteria as I have maintained FC all winter, right ?

    thx
    12k SWG pool, free form. 1HP flotec pump, P90 Leslie's filter. Florida. Taylor 2006 test kit. I think plaster, waiting verification from here.

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