Become a TFP Supporter Pool Math Forum Rules Pool School
Results 1 to 10 of 10

Thread: Bad CYA? level not increasing as predicted

  1. Back To Top    #1

    Join Date
    May 2015
    Location
    Ann Arbor, MI
    Posts
    30

    Bad CYA? level not increasing as predicted

    Hello all!

    We are in our secong year of pool ownership, but earlier this year we converted successfully from Baqua and have never looked back. But now we are having some concerns as regards the balance of CYA and chlorine in our full sun situation. Pool has been trouble free since the conversion.

    On 7/14 a simple evening top up of our water turned into an accidental overnight flood (left the hose on) followed by a backwash to bring the water level back down, and a subsequent examination of current chemical status. My DH had been keeping the CYA at what he thought was 30, and the rate of chlorine use indicated that we needed to increase that to compensate for full sun. We had added CYA a little over a week before to increase it to what we thought would be 50. The pool really does get full sun all day every day, and we have a clear bubble solar cover (new, installed after the baqua conversion). After the flood, the water looked greenish the next day, but no CC present. We are on well water, but no super high levels of metals or anything.

    After the unplanned dilution situation, our levels on 7/15 morning were:

    FC 2.5 ppm
    CC <0.5 ppm
    TA 210 ppm
    CYA 40 ppm
    pH 7.5

    We added the requisite chlorine to hit 6 ppm. I added a CYA sock to get just above 50 ppm. I added muriatic acid to lower pH to 7.2, and had kids splash to start the aeration necessary to start lowering the high TA. I did not check CYA or pH until today.

    When I tested today (7/17), the CYA seems to be about 40-43 ppm (I massaged the sock so it got into the water within 24 hours), and our FC still drops to zero every night... We are using so much chlorine, it feels crazy. I plan to do an OCLT tonight and check for CC. Today, we also noted a lot of yellowy sediment on the bottom of the pool that vacuumed easier than dirt (live algae? dead algae? nothing of concern?). The water is truly crystal clear today, no longer green. pH is 7.2. Do I need to keep waiting to see if the CYA will go up, even though the sock has been emptied, or is this what it really is?

    I read in a different thread somewhere that if it were bad CYA or not what the canister claimed (what we have used up to this point comprised 4 4-lb canisters of HTH brand purchased from Meijer) it would obviously not bring the level up as expected. I have a new 6-lb canister of a different brand bought at an actual pool store and will use that to get it up to 50 ppm (after I hear back from you all whether or not I should wait longer for the last batch). From now on we will add Cl at night, but still it is getting down to unacceptable levels by the end of the day.

    Thoughts? We're confused. We appeal to your expertise!
    30,000 gallon in-ground marblelite pool, built ~1968, 18x37
    Hayward Perflex DE Filter, EC-65 (or 75?)
    Hayward Super Pump, 1 HP/230V, 2013
    Aquabot G-Jet, well water, Taylor TF-100 test Kit
    Renovation of marblelite and retiled in 1999

  2. Back To Top    #2

    In the Industry

    duraleigh's Avatar
    Join Date
    Apr 2007
    Location
    Sebring, Florida
    Posts
    30,085

    Re: Bad CYA? level not increasing as predicted

    1. Give your CYA a chance to increase it often takes 4 days or even up to a week to register correctly on the test.

    2. You will need to SLAM your pool, There is an article in Pool School that will explain it to you and you must follow that process to a T to get your pool back sparkling.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  3. Back To Top    #3
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,623

    Re: Bad CYA? level not increasing as predicted

    If you added 16 lbs (256oz) of CYA to your 30k gallon pool, that will raise your CYA by 64ppm.

    Do not add anymore CYA to your pool. Also, make sure you doing the CYA test as describe in bright outdoor lighting with your back to the sun and the vial at waist height. Do the test several times with the same sample until you feel your results are consistent.

    Was the product you added >99% cyanuric acid?


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  4. Back To Top    #4

    Join Date
    May 2015
    Location
    Ann Arbor, MI
    Posts
    30

    Re: Bad CYA? level not increasing as predicted

    Thanks all. The CYA was 96%, added some after the conversion (to get up to 30 ppm based on est 30K pool volume, but my DH never tested to confirm that it made it up to that level). The next time we added was about a week before the flood, it tested at 40 after the flood, two days ago. The fact that we had some FC left that morning was very encouraging, but since then we have not had that situation. Added about 10 ppm worth of CYA that day to get it back up to 50. I will wait the rest of the week and see if it continues to rise. Testing today (in about the conditions JoyfulNoise noted) got about 43.

    We have never registered any significant CC since converting from Baqua, and the pool water is as clear as can be... could you teach me why a SLAM is necessary under those conditions? Thanks!
    30,000 gallon in-ground marblelite pool, built ~1968, 18x37
    Hayward Perflex DE Filter, EC-65 (or 75?)
    Hayward Super Pump, 1 HP/230V, 2013
    Aquabot G-Jet, well water, Taylor TF-100 test Kit
    Renovation of marblelite and retiled in 1999

  5. Back To Top    #5
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,623

    Re: Bad CYA? level not increasing as predicted

    Quote Originally Posted by themitzelfamily View Post
    Thanks all. The CYA was 96%, added some after the conversion (to get up to 30 ppm based on est 30K pool volume, but my DH never tested to confirm that it made it up to that level). The next time we added was about a week before the flood, it tested at 40 after the flood, two days ago. The fact that we had some FC left that morning was very encouraging, but since then we have not had that situation. Added about 10 ppm worth of CYA that day to get it back up to 50. I will wait the rest of the week and see if it continues to rise. Testing today (in about the conditions JoyfulNoise noted) got about 43.

    We have never registered any significant CC since converting from Baqua, and the pool water is as clear as can be... could you teach me why a SLAM is necessary under those conditions? Thanks!
    If you have 0 CC's and clear water but higher than expected FC consumption, I would advise you to perform an overnight chlorine loss test (Perform the Overnight FC Loss Test (OCLT)). If you experience more than a 1ppm FC loss overnight, then a SLAM is indicated.

    - - - Updated - - -

    I also see from your signature that you fill with well water. Has your pool water been tested for the presence of metals (Fe and Cu)? Has your well water been tested as well? I'm just curious and it is always good to know what's coming out of the well water.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  6. Back To Top    #6

    Join Date
    May 2015
    Location
    Ann Arbor, MI
    Posts
    30

    Re: Bad CYA? level not increasing as predicted

    Thank you for that... I was planning to do the OCLT tonight and will report back. And thanks for the suggestion about testing. Next time I need to go to the pool store I will also have them test for metals in both well and pool samples. We don't have to top up too often since it has been a rainy year, but this recent flood might have changed levels in a more significant way. We have a a small amount of what must be rust staining below the skimmer inlet... Perhaps the previous owner filled via the skimmer? So iron is always a possibility.
    30,000 gallon in-ground marblelite pool, built ~1968, 18x37
    Hayward Perflex DE Filter, EC-65 (or 75?)
    Hayward Super Pump, 1 HP/230V, 2013
    Aquabot G-Jet, well water, Taylor TF-100 test Kit
    Renovation of marblelite and retiled in 1999

  7. Back To Top    #7

    Join Date
    May 2015
    Location
    Ann Arbor, MI
    Posts
    30

    Re: Bad CYA? level not increasing as predicted

    Soooo... Thinking you might be right about an impending SLAM. At dusk I tested the water for the first part of the OCLT, and our FC was zero. I dumped in couple gallons of 12.5% Cl and am letting it mix for a couple hours, then I'll test again tonight. I had put in 2 gal at 3 PM. Hmmm.
    30,000 gallon in-ground marblelite pool, built ~1968, 18x37
    Hayward Perflex DE Filter, EC-65 (or 75?)
    Hayward Super Pump, 1 HP/230V, 2013
    Aquabot G-Jet, well water, Taylor TF-100 test Kit
    Renovation of marblelite and retiled in 1999

  8. Back To Top    #8
    JoyfulNoise's Avatar
    Join Date
    May 2015
    Location
    Tucson, AZ
    Posts
    11,623

    Bad CYA? level not increasing as predicted

    Quote Originally Posted by themitzelfamily View Post
    Soooo... Thinking you might be right about an impending SLAM. At dusk I tested the water for the first part of the OCLT, and our FC was zero. I dumped in couple gallons of 12.5% Cl and am letting it mix for a couple hours, then I'll test again tonight. I had put in 2 gal at 3 PM. Hmmm.
    So your pool consumed ~ 8ppm FC in 5 hours .... Yeah, you might need to SLAM that water. Stock up on bleach, you're gonna need it...


    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

  9. Back To Top    #9

    Join Date
    May 2015
    Location
    Ann Arbor, MI
    Posts
    30

    Re: Bad CYA? level not increasing as predicted

    Morning test results:
    FC = 5.5 ppm (drop of 3 ppm)
    CC = <0.5 ppm

    Looks like a SLAM, starting tonight.
    30,000 gallon in-ground marblelite pool, built ~1968, 18x37
    Hayward Perflex DE Filter, EC-65 (or 75?)
    Hayward Super Pump, 1 HP/230V, 2013
    Aquabot G-Jet, well water, Taylor TF-100 test Kit
    Renovation of marblelite and retiled in 1999

  10. Back To Top    #10

    Join Date
    May 2015
    Location
    Ann Arbor, MI
    Posts
    30

    Re: Bad CYA? level not increasing as predicted

    I also read in the SLAM instructions that anytime your FC gets to zero you should SLAM. Given that, we should have done this a while back since our CYA level was too low and the sun was eating our chlorine by the end of the day.

    "Experience is the best eacher, and the most expensive." True story.
    30,000 gallon in-ground marblelite pool, built ~1968, 18x37
    Hayward Perflex DE Filter, EC-65 (or 75?)
    Hayward Super Pump, 1 HP/230V, 2013
    Aquabot G-Jet, well water, Taylor TF-100 test Kit
    Renovation of marblelite and retiled in 1999

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •