Become a TFP Supporter Pool Math Forum Rules Pool School
Page 1 of 2 12 LastLast
Results 1 to 20 of 35

Thread: How likely is CYA zero from 40 last year?

  1. Back To Top    #1

    How likely is CYA zero from 40 last year?

    Hi,
    I am just opening our 18,000 gallon gunite pool, and I am using chlorine at a rapid rate as I get the water clean.
    I finally did a CYA test today, and the results were surprising -- I detected NO CYA.
    I am definitely going to re-test, but thought I should ask... How likely is this after the pool has consistently had CYA levels (for many YEARS) of between 40 and 60?


    Thanks,
    David
    18,000 gallon, in-ground gunite pool
    Hayward C-1750 Cartridge filter
    3/4 hp pump
    in Sunny Northern California

  2. Back To Top    #2
    Texas Splash's Avatar
    Join Date
    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,962

    Re: How likely is CYA zero from 40 last year?

    When was the last time you checked CYA and/or added any stabilizer? It is possible to lose it and certainly does happen, especially if some environmental conditions are perfect and FC drops to zero. Now might be a good time to post a full set of test results for us with your TF-100 or Taylor K-2006.
    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
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  3. Back To Top    #3

    Join Date
    Aug 2014
    Location
    Northern IL
    Posts
    4,615

    Re: How likely is CYA zero from 40 last year?

    Pat has you. I am wondering also: was there any cloudiness to the CYA mixture in the vial?

  4. Back To Top    #4

    Re: How likely is CYA zero from 40 last year?

    Hi Marion,
    Not at all... So I will re-test, but wonder also if there is a shelf life to the reagent...


    Quote Originally Posted by MarianParoo View Post
    Pat has you. I am wondering also: was there any cloudiness to the CYA mixture in the vial?
    - - - Updated - - -

    Hi Tex,
    The last time I checked it was last fall. It has been checked about 20 times over the years, whether by myself and/or the pool supply store, and it was always in that 40 to 60 range, and always after being winterozed very carelessly (like almost not at all).

    Thanks,
    David

  5. Back To Top    #5
    Texas Splash's Avatar
    Join Date
    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,962

    Re: How likely is CYA zero from 40 last year?

    That R-0013 is perhaps the most stable reagent in the kit. It should last a good long while as long as it was stored in a cool place away from the sun. I've had mine for 2-3 seasons with no problem.
    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
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  6. Back To Top    #6

    Join Date
    Aug 2014
    Location
    Northern IL
    Posts
    4,615

    Re: How likely is CYA zero from 40 last year?

    No need to retest. I was just wondering as sometimes if there is cloudiness it can indicate that you have some CYA, but not measurable CYA. Occasionally people think it is zero and adjust for that and there actually is SOME in the water and they end up higher than target. That's one of the reasons I asked.

    How old is your reagent? Also, like Pat said, give us a full set of results.

  7. Back To Top    #7
    Texas Splash's Avatar
    Join Date
    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,962

    Re: How likely is CYA zero from 40 last year?

    David, my battery is low and I'm about to turn-in for the night. So I don't want to leave you hanging. I haven't seen your test results yet, but I'm assuming your FC must be very low right now or non-existent. Would that be true? Also wondering if your CC level is elevated. So there are two options to consider here: Either you simply have organics/algae that is consuming FC very quickly and you need to stick with a SLAM, .... OR with no CYA and FC depleting exceptionally fast, your CYA may have converted to something else like ammonia. With no tests I can't tell for sure. But I would still consider conducting this test first:
    - Add only enough bleach to get your FC to 10. Test it again in 10 minutes. If your FC held between 5-10, then increase it to 12, then add stabilizer for a target of 30, and perform a SLAM (link below) like normal. If your FC fell below 5 after just 10 minutes, increase it back immediately and test again in 10 minutes. Continue this cycle until the FC holds after 10 minutes.

    As you can see, either way it's very important to stay on-top of the FC testing in this early stage - every 10 minutes at first. It's required to allow the FC to hold better and overtake what's in the water. Now if the 10-min drill doesn't work after a couple hours, you do have the option of doing a partial drain to remove some of the bad water if you prefer to help kick-start the cleaning process a little better. Some situations find that a partial water exchange might be more cost-efficient at first. But you would still need to SLAM once filled back up. If water exchange and time are a factor, I would go right to the 10-min drill first. But make sure to have a good amount of bleach ready when you do.

    David, you'll need to watch the FC very closely for the first couple hours or so until it breaks this "fever". Don't add stabilizer until you see the FC is holding on its own past 10 minutes. Let us know if you have any problems or questions.
    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
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  8. Back To Top    #8

    Re: How likely is CYA zero from 40 last year?

    Hi Tex,
    Thanks very much for the great step-by-step advice! The pool was dark green upon start-up, but it is 100% my fault. The pool is at my Mother-in-Law's house, and I do not go over enough except in the summer, when our kid swims every day. At least a good deal of the chlorine use is legit. The pool is now blue but somewhat cloudy (visibility to about 2 feet).
    I will head over there and test in the morning and report back.


    Thanks Again!
    David
    18,000 gallon, in-ground gunite pool
    Hayward C-1750 Cartridge filter
    3/4 hp pump
    in Sunny Northern California

  9. Back To Top    #9

    Join Date
    Aug 2015
    Location
    Folsom Prison, CA
    Posts
    116

    Re: How likely is CYA zero from 40 last year?

    Has the pool been covered? My CYA level has lowered a bit due to the heavy rain we have had this year and then some evaporation/refill from the last couple weeks.
    Jeff || 19,000g IGP || SwimClear 3025 Cartridge Filter || Hayward TriStar 1.39 THP pump || K-2006 Test Kit || 80% Surface Coverage Heliocol || Hayward Controller || Hayward Phoenix 4X4 || "Solar Rings" || PoolSkim

  10. Back To Top    #10
    mikemass's Avatar
    Join Date
    Jul 2013
    Location
    Northern Howell, NJ
    Posts
    484

    Re: How likely is CYA zero from 40 last year?

    Following this web site it seems more and more people are reporting full CYA loss over the winter. Bacteria derogating and converting into ammonia seems to be the cause. Did you have a significant amount of dead organic stuff on the bottom? Earthworms, decaying leaves, mouse, toads, etc. Also what kind of cover do you have? Solid or mesh?
    25 + year pool owner. Current pool (going on 11th year) - 38K gallon in ground Gunite/White Plaster, Spillover Spa, Hayward Cartridge Filter, Hayward 450k BTU NG Heater, Hayward Goldline Aqua Logic control with T-Cell-15 Salt Water Cell, Dolphin Explorer.
    You Need: Bleach, a A Test Kit & a Bookmark to "Pool School". Now what's your question?

  11. Back To Top    #11
    Pool Tool's Avatar
    Join Date
    May 2014
    Location
    Western Chicago Area, IL
    Posts
    754

    Re: How likely is CYA zero from 40 last year?

    It is pretty common for me to open to CYA of zero (or at least <20) after closing around 40. I usually add 20 ppm, adjust FC as if it were 30 then retest in a week. My pools is always full of worms and some leaves when i open no matter how tight my cover is.
    16' x 32' (21100 gal), vinyl, 1.5 hp Hayward SuperPump,
    Tagelus TA60/60D Sand Filter, Raypak 399K Digital Heater, TF-100

  12. Back To Top    #12

    Re: How likely is CYA zero from 40 last year?

    Quote Originally Posted by censored View Post
    Has the pool been covered? My CYA level has lowered a bit due to the heavy rain we have had this year and then some evaporation/refill from the last couple weeks.

    The pool was not covered, so great catch!

    - - - Updated - - -

    Hi Mike,
    Thanks for the reply! No mouse or toad -- at least not yet (I'm still cleaning and cannot see the bottom), but a fair amount of leaves that I am nearing the end of.


    Thanks,
    David

    - - - Updated - - -

    Hi Fellow Packer Backer,
    This us great advice. I re-read Tex's recommendation, and due to the severe drought here in California, I do not have the option of a partial drain of the pool.
    I will report back with test results, and go with the SLAM process.


    Thanks,
    David
    18,000 gallon, in-ground gunite pool
    Hayward C-1750 Cartridge filter
    3/4 hp pump
    in Sunny Northern California

  13. Back To Top    #13

    Re: How likely is CYA zero from 40 last year?

    Hi Guys,
    I am wondering if these conditions make DiChlor an attractive option? Maybe two birds with one stone... How much does each bag of powdered shock raise CYA?


    Thanks,
    David
    18,000 gallon, in-ground gunite pool
    Hayward C-1750 Cartridge filter
    3/4 hp pump
    in Sunny Northern California

  14. Back To Top    #14
    Texas Splash's Avatar
    Join Date
    Jun 2014
    Location
    South-Central Texas, Marion/San Antonio
    Posts
    12,962

    Re: How likely is CYA zero from 40 last year?

    Dichlor is fine to use when you need to increase both FC and CYA. You can use the Poolmath calculator's "Effects of Adding Chemicals" row to tell you what you expect based on the amount you plan on using. For a SLAM, you can expect that bleach will still be your primary sanitizer. If the Dichlor doesn't increase CYA as quickly as you would like, stabilizer may still be required.

    If you haven't yet done that 10-min drill, I would stick to the bleach at first. It's fast-acting and won't raise CYA which you don't want to do until you know for sure you can hold some FC to rule-out ammonia. Do that first, then sure ... bombs-away with dichlor using the calculator.
    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
    Vital Links: POOL SCHOOL, RECOMMENDED LEVELS, RECOMMENDED CHEMICALS, Poolmath Calculator, SLAM, Chlorine/CYA CHART.
    If you enjoyed your TFP experience, please consider donating to Support TFP!

  15. Back To Top    #15

    Re: How likely is CYA zero from 40 last year?

    Hi All,
    The test results are in...

    Gunite pool, 18,000 gallons

    FC = 1
    CC = 2
    PH = 7.0
    TA = 120
    CH = 180
    CYA < 20

    I used a fresh CYA reagent. I had dumped 4 gallons of 12.5% liquid chlorine in yesterday...
    The pool is slowly clearing (our method is to note how many steps on the shallow end we can see -- currently, it is a little more than one), but clearly I need some stabilizer.
    My plan is to add enough chlorine to get the pool to 24 ppm and also try to add some stabilizer.
    Question: how quickly does Dichlor add CYA?

    Thanks,
    David

  16. Back To Top    #16

    Join Date
    Aug 2014
    Location
    Northern IL
    Posts
    4,615

    Re: How likely is CYA zero from 40 last year?

    I would suggest doing Pat's (Texas Splash) 10 minute drill before adding dichlor or CYA.

  17. Back To Top    #17

    Re: How likely is CYA zero from 40 last year?

    Hi Tex,
    Sorry, it looks like my reply from a little while ago didn't post...
    I will definitely use the bleach/liquid chlorine method you describe. I don't have stabilizer on hand anyway...

    Thanks,
    David

  18. Back To Top    #18

    Re: How likely is CYA zero from 40 last year?

    Hi All,
    Sorry -- we were gone for a week. Now I am back at it...
    Before I left I added enough stabilizer to get the CYA level (which seemed to be non-existent, and that was confirmed with two tests and new reagent) up to 45. I also added enough chlorine to get FC to about 22, to further eradicate any remaining algae.
    Upon my return, I just tested CYA, FC and CC. My results were:

    FC 2
    CC about 1.5
    CYA 45
    PH 6.8

    The pump is not straining (the gauge on the filter is at 2 pounds over "clean").
    I vacuumed before leaving, and brought up fairly little at this point.
    Our unofficial clarity guide is to check how many steps we can see on the shallow end. Out of three steps, two are now clearly visible and the bottom step is fuzzy, but visible.
    My approach now is to shock the daylights out of the pool until it further clears (and holds chlorine overnight). Anything else I may be missing? I was going to address PH once FC holds overnight and then comes back down into the normal range...or should I address it sooner?

    Thanks,
    David

  19. Back To Top    #19

    Join Date
    Aug 2014
    Location
    Northern IL
    Posts
    4,615

    Re: How likely is CYA zero from 40 last year?

    Did you test the TA?

    Since 6.8 is the lowest the pH test can measure, I would raise it with borax if your TA is fine or high, washing soda if TA is under 50. Go slow so you don't overshoot.

    Once pH is 7.0-7.4, SLAM away!

  20. Back To Top    #20

    Re: How likely is CYA zero from 40 last year?

    Hi Marian,
    TA is 120. I will look up the scale and proceed according to your advice. Thanks!

    David
    18,000 gallon, in-ground gunite pool
    Hayward C-1750 Cartridge filter
    3/4 hp pump
    in Sunny Northern California

Page 1 of 2 12 LastLast

Posting Permissions

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