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Thread: CYA Test results different

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    CYA Test results different

    Hi all,
    I am having a hard time maintaining chlorine levels. We went on vacation for 3 weeks and left my neighbor teenage boy in charge. Specifically asked to use bleach, every other day add a gallon. If it rained, add more, etc... Unfortunately, we had a week of tremendous heat and a second week of rain all week (perfect storm for algae)! Pool got B.A.D, according to teenager. He shocked it, according to pool store instructions (Booooo... he didn't understand that we DON'T use pool chemicals)... anyway, he tried. Pool was close to OK when we got back, just a little cloudy, nothing major. I've been trying to get it back to normal but I am not able to maintain chlorine levels. Also, PH has been higher (8.2), so I added the Muriatic Acid. Dropped it to 8.4.
    Now, since I've been back, I have been using my new FT100 test kit and the 3 times I tried, I got a VERY high CYA result (90+). I lost sight of the black dot almost immediately after adding the mix. However, when I take the water to Leslie's Pool, they always come back saying the CYA is fine (at 70). I asked them specifically to pay close attention to that CYA test and they checked twice (on the three different occasions that I went)... so I wonder what is going on with such different results... My questions are:
    1. Is high CYA responsible for loss of chlorine?
    2. Where is the CYA results most likely mistaken? My testing with FT100 or Pool store?
    3. Does Muriatic Acid go bad after a while? Last year I purchase a 6-pack and I still had 4 gallons left, so that is the MA I used last week to get the PH lowered.
    4. Anything else I might be missing to get this stable?
    5. Can shocking (with bleach) bring the PH up high?
    6. Oh, husband is wondering, does CYA evaporate with normal water evaporation? It has been so hot that we have probably lost about 1 foot of water (1/6 the size of our pool). I figured no, because the CYA wouldn't evaporate with the H2O... he thinks it might, so why is the CYA still so high (if it is), why hasn't it gone down at least a little.

    Oh, last night I added a gallon of chlorine, this morning CC was 0, I shocked it (with Bleach) because I saw some yellow starting to form on the walls, added 4 gallons bringing the CC up to 27 this evening. Unfortunately it may have raised the PH (although I find it harder to read the PH at night, since it is hard to distinguish between different shades of bright pink with low light.

    CC: 27
    PH: 8.2
    CYA: (FT100 results 90+)
    TA:124
    CH: Totally forgot to check for this one tonight.
    Pool size: 13000 gallons/white plaster/ozonator with chlorine

    THANKS IN ADVANCE FOR THE HELP!! I hadn't had any trouble for one year, and then I dared go on vacation!!! =D
    Built in 2014, 18,000gal, plaster, in ground, Pentair Clean & Clear Plus 2.0 HP, Booster Pump, Cartridge filters, inline chlorinator, automatic cleaner, Pentair MasterTemp 400 heater, Silencer for SPA.
    Bloody hot summers in Katy, TX; the rest of the year is just plain hot!

  2. Back To Top    #2
    linen's Avatar
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    Re: CYA Test results different

    I assume the CC (Combined Chlorine) number you listed above was actually FC (Free Chlorine)? Do you know what your CC level is?

    The ph test is not valid above 10 ppm FC so don't adjust now.

    DO NOT trust pool store cya measurements, they get this wrong more than right. Most likely your is close and it indicates you need to do a drain refill. Please explain the 90+ reading...was it 90 or not?
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  3. Back To Top    #3

    Re: CYA Test results different

    Yes, level posted was FC!!! Sorry!! CC was zero.
    Since I ran 3 CYA tests with the FT100, the first test came to 100, one week ago. Then Pool store said it was fine (3 different times). Yesterday and today, I tested again for CYA, and two times I got 90.
    THANKS!
    Built in 2014, 18,000gal, plaster, in ground, Pentair Clean & Clear Plus 2.0 HP, Booster Pump, Cartridge filters, inline chlorinator, automatic cleaner, Pentair MasterTemp 400 heater, Silencer for SPA.
    Bloody hot summers in Katy, TX; the rest of the year is just plain hot!

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    foobert's Avatar
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    Re: CYA Test results different

    Quote Originally Posted by mvoorn
    Hi all,
    1. Is high CYA responsible for loss of chlorine?
    2. Where is the CYA results most likely mistaken? My testing with FT100 or Pool store?
    3. Does Muriatic Acid go bad after a while? Last year I purchase a 6-pack and I still had 4 gallons left, so that is the MA I used last week to get the PH lowered.
    4. Anything else I might be missing to get this stable?
    5. Can shocking (with bleach) bring the PH up high?
    6. Oh, husband is wondering, does CYA evaporate with normal water evaporation?
    1) no. High CYA is responsible for reducing chlorine's effectiveness. Thus, high CYA requires higher levels of FC to have the same sanitizing effect.
    2) Trust your measurements: in broad daylight, keep your back to the sun, and hold the tube at waist level.
    3) Should be fine.
    4)
    5)
    6) Nope, only draining water will reduce it (excluding letting it go to swamp mode).
    ~john
    24.5K G, pebble, SuperFlo VS 1.5, 48sq DE filter, Hayward H250FDN, Autopilot RC-52, Poolvergnuegen & 3 daily swimmers in season.

  5. Back To Top    #5

    Join Date
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    Re: CYA Test results different

    Well, 5 is not really a simple yes or no. Bleach/Liquid Chlorine is basic, so will raise the pH when you add it. However, when it gets used up, that is an acidic process, which brings the pH back to where it started. So it is a net neutral process. Also, when the FC is above 10 the pH test can read artificially high.
    John
    7 year old ~13,500 gal 24' AGP with 1.5 hp Proline pump, 150 sqft Pleatco cartridge, filled with well water with pH of about 4.5.
    Wanda the Whale pool vacuum, home made heater, Taylor K-2006
    Cloudy Pool? 1) Order test kit. 2) Follow SLAM
    New to TFPC? Read Pool School a few times, then post questions. PoolMath will help with chemical additions.

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    Re: CYA Test results different

    On #6, you don't lose anything but chlorine and water to evaporation. As it evaporates your CYA actually rises slightly but then goes back when you top off.

    You can either SLAM now or lower your CYA and SLAM after that. It would be much easier to lower your CYA first, but it's your call. If you choose to SLAM now let your FC drop below 10 so you can get an accurate pH reading and get it lowered to 7.2 since you won't be able to test it during the SLAM.
    JD - 28' Round Above Ground Pool, 17,000 Gallons. Dual speed Jacuzzi pump with cartridge filter. Dual speed 1 HP pump, Hayward S210T sand filter
    Pool School - PoolMath - HIGHLY Recommended Test Kits

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    linen's Avatar
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    Re: CYA Test results different

    Okay, I would assume your cya is 90 ppm. I would recommend doing a ~50% drain/refill before continuing the shock process (we call it the SLAM process now) to get your cya down to ~50 ppm.
    TFP Expert who uses Pool School and my TF100 test kit along with PoolMath for my: Round 11K gallon AGP with deep end, 20" sand filter, Matrix 1hp 2spd, 6 2ftX20ft solar panels (and solar cover!), Intex SWCG (copper bars disconnected) and a Rubadub hot tub (chlorine). The SLAM process is not finished until: 1. CC < 0.5 ppm, 2. An OCLT < 1.0 ppm and, 3. The water is crystal clear.

  8. Back To Top    #8

    Re: CYA Test results different

    Appreciate all the responses and help! I will test CYA in daylight with back against sun one more time (I've always tested inside the house). Most likely CYA is still high (maybe a little less high), but it seems like I will have to drain some of the water!
    Built in 2014, 18,000gal, plaster, in ground, Pentair Clean & Clear Plus 2.0 HP, Booster Pump, Cartridge filters, inline chlorinator, automatic cleaner, Pentair MasterTemp 400 heater, Silencer for SPA.
    Bloody hot summers in Katy, TX; the rest of the year is just plain hot!

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    Jeetyet's Avatar
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    Re: CYA Test results different

    Since you have a good test kit and seem so surprised by your present CYA level I'm going to assume that it was much lower the last time you checked it (before vacation), so I would surmise that your current high level was most likely caused by whatever the pool store had the kid dump in the pool to shock it.
    "The early bird might get the worm, but its the second mouse that gets the cheese." ~ W. Rian Adams
    .
    Relative's IG Vinyl | 16x32 | ~18,600 gals | Hayward 3/4hp Pump | Hayward S244T Filter | Pentair Model 300 Chlorinator (not used) | Polaris 180

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    Re: CYA Test results different

    A couple of principles you can take away from this thread...

    1. If you have a good test kit like the K-2006 or the TF-100, trust your own testing..ALWAYS

    2. Nothing very good ever comes from stepping foot inside the pool store.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

  11. Back To Top    #11

    Re: CYA Test results different

    Quote Originally Posted by Jeetyet
    Since you have a good test kit and seem so surprised by your present CYA level I'm going to assume that it was much lower the last time you checked it (before vacation), so I would surmise that your current high level was most likely caused by whatever the pool store had the kid dump in the pool to shock it.
    YUP! CYA was 60 before I went on vacay! =(
    Built in 2014, 18,000gal, plaster, in ground, Pentair Clean & Clear Plus 2.0 HP, Booster Pump, Cartridge filters, inline chlorinator, automatic cleaner, Pentair MasterTemp 400 heater, Silencer for SPA.
    Bloody hot summers in Katy, TX; the rest of the year is just plain hot!

  12. Back To Top    #12

    Re: CYA Test results different

    Quote Originally Posted by duraleigh
    A couple of principles you can take away from this thread...

    1. If you have a good test kit like the K-2006 or the TF-100, trust your own testing..ALWAYS

    2. Nothing very good ever comes from stepping foot inside the pool store.
    I couldn't agree more than statement #2 ! Since nobody really believes in the BBB method around me, it is really hard to let others take care of my pool if I go on vacation during the hottest months of the year (which is when constancy is needed to avoid a sprouting of algae!)! I don't know why I still doubt myself when testing with my TF-100... I never have problems (until I go on vacation, hahaha)! Imagine the amount of work and money I would save if I just stop vacationing and stay tied to my pool maintenance!!

    So how do you guys do it when you leave home? How do you keep it from going bad?
    Built in 2014, 18,000gal, plaster, in ground, Pentair Clean & Clear Plus 2.0 HP, Booster Pump, Cartridge filters, inline chlorinator, automatic cleaner, Pentair MasterTemp 400 heater, Silencer for SPA.
    Bloody hot summers in Katy, TX; the rest of the year is just plain hot!

  13. Back To Top    #13

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    Re: CYA Test results different

    old thread but i use a peristaltic (sort of stenner) pump to add basic chlorine need of the spa. Works fine and i'm free to go to holiday. When i come back i run a full test, usually it ends up with some Muriatic Acid to take PH down to 7.5
    Arctic Spa Klondike Legend SE
    AG / Filter Cardtrige 50m2/ TFP / borates / TF100
    478 gallon @ 99.5-103.1 F Depending on season
    Ozonator disconnected

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