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Thread: CYA numbers bouncing around or bad testing?

  1. Back To Top    #1
    Guest

    CYA numbers bouncing around or bad testing?

    Hi guys,

    So recently I went through a large drain/refill to get my CYA numbers down. Supposedly before the drain I had 150ppm (or more) CYA. Before drain I had 16078 gallons, and after draining I had 5032 gallons of original water left. Then I refilled back to the ~16k gallon mark. After the week of slowly refilling the pool with well water here was my test results (from the store):

    Temp 75
    saturation index 0
    CYA 61
    TC 3.9
    FC 3.1
    pH 7.3
    TA 191
    Adj TA 173
    Tot hardness 256
    Copper 0.5ppm
    Iron 0

    Around this same time, another test from another store gave me a CYA of 40

    I then shocked my pool to ~24ppm, and shocked again a day later to my guess of 12ppm. I haven't added any chemicals in the past week, just filtering as much as possible. Here are my current test results:

    Temp 77
    saturation index 0.9
    CYA 119
    TC 9
    FC 7.9
    pH 8.1
    TA 214
    Adj TA 178
    Tot hardness 282

    I was not expecting the CYA to jump up like that. I even had them test again (manually, instead of in the machine). Is there something like my relatively higher FC that could be affecting CYA to make it inaccurate? Or do I need to drain again?

    I've attached some pictures of the pool...vinyl liner is very old and wrinkled, and concrete has seen better days. Also the skimmer line is leaking, so it is plugged off in the skimmer and disconnected from the pump, as you can see. Not sure what the 3rd tall PVC line is, maybe it's a winterizing line or something.

    Big question is this: If my CYA is where I'm hoping it was, in the 40-60ppm range, then my FC is fine. But if my CYA is really that high at 119ppm, I'm going to have to go through the entire draining cycle again, which was a pain in the butt and a strain on my well.

    Also, any other suggestions on what to adjust in my chemistry, and what order? I know pH is a little higher and hardness too.
    Attached Images Attached Images

  2. Back To Top    #2
    Richard320's Avatar
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    Re: CYA numbers bouncing around or bad testing?

    Bad testing.

    Unless of course, you have been shocking the pool with some sort of powdered chlorine. inconsistency-in-readings-t61728.html Study the history of readings in that first post.

    The obvious solution, and this tends to apply to almost any water chemistry problem presented here, is: Get your own test kit.
    16K freeform gunite with spa; Pentair 4000 DE filter; Century Whisperflow 1 HP; Pentair Minimax heater.
    Troublefree does not mean Maintenancefree. It's like brushing your teeth: You can spend a couple minutes a day and pennies a week or go to the dentist once a year and spend several thousand dollars.
    A pool is like a pet - you have to feed it every day, even the days you don't want to play with it!

  3. Back To Top    #3
    Guest

    Re: CYA numbers bouncing around or bad testing?

    I was only adding liquid chlorine.

  4. Back To Top    #4

    Join Date
    Jun 2012
    Location
    Howell, NJ
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    977

    Re: CYA numbers bouncing around or bad testing?

    Since you only added liquid chlorine, probably testing error. Now you can see why we don't trust pool store testing. Like Richard said, if you want to take control of your pool, you will need to get one of the recommended test kits, which are conveniently linked to in my signature.
    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.

  5. Back To Top    #5
    Mod Squad kimkats's Avatar
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    Re: CYA numbers bouncing around or bad testing?

    I had three different stores (two were the same just on different sides of town) test my pool water. It was all a sample taken from one area at the same time.

    I got three completely different test results! The money to "fix" my problems ranged from $75 and $125 and to bring back more water after I put in the stuff they wanted to sell me. I just walked out laughing!

    See I had tested my water with MY pool kit and it was RIGHT on the money. My water looked great and felt great! There was NOTHING wrong with my water. I even told the pool store the water looked fine. "Oh but there WILL be problems if you do not buy and put in.....". LOL

    Kim
    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

  6. Back To Top    #6
    Guest

    Re: CYA numbers bouncing around or bad testing?

    Yeah, so I went ahead and got a test kit, but it probably won't arrive for a week. I was putting it off because constantly buying new reagents is annoying, but I guess that's the price to pay.

  7. Back To Top    #7
    Mod Squad kimkats's Avatar
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    Re: CYA numbers bouncing around or bad testing?

    I ordered my test kit when I ordered my pool. I went ahead and ordered the reagents I knew I would need the most as well. I used it last summer and am still using it this summer. I think I will have plenty for next summer so...........

    Kim
    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

  8. Back To Top    #8

    Join Date
    Jun 2013
    Location
    SpringHill FL
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    Re: CYA numbers bouncing around or bad testing?

    Keep your kit inside in a climate controlled area of your home. You will run out of reagents before they go bad if you do that.
    Nathan
    15x30 gunite 18k gallons Hayward star clear plus 120sqft cart

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