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Thread: my first chemistry numbers

  1. #1
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    Default my first chemistry numbers

    I purchased a house recently with a pool. It was a beautiful deep green algae color(the pool not the house). I had a pool "pro get me started. It is now pretty clean. I feel I am on the home stretch. I finally purchased a taylor k2006 test kit and tryed it out.
    fc 5.5
    tc 5.5
    ta 120ppm
    cya 115ppm (uh-oh)
    ph 7.8 ( a little high)
    ch 230 ppm.

    My pro had me use the wonderfull pucks. I suspect this is where my high cya #'s came from. I have been using clorox bleach since i discovered this forum a month or two ago. I have not had to use much (I believe because of the cold weather.) I am no longer using the pucks.
    From what I have gathered the only real practical way to lower cya's is to drain a portion of the pool and refill. Is this correct?, Am I missing anything?
    I feel since my cya is so far off this is the first thing to fix before I adj ph.
    Any comments or questions are welcome Yhanx everyone!
    gunite inground 11.5k gal pool w/ attached 800 gal spa - Purex triton clean & clear plus 320 - Polaris 280 robot -
    Raypak 265b heater

  2. #2
    aylad's Avatar
    aylad is offline SuperMod Emeritus Burfle Ringer aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars
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    Default Re: my first chemistry numbers

    Hello Dizzle, and welcome to the forum!!

    Congrats on the new house and pool, and I'm impressed that you've done your homework as far as pool maintenance. You'll find that controlling your own pool will make life MUCH easier and the pool much more enjoyable.

    In answer to your question, yes, the only practical way to lower the CYA is to do a partial drain and refill. You can up your chlorine levels to compensate for the high CYA, but yours is high enough that even that option is iffy at best. With this being the beginning of the season, I very strongly encourage you to drain/refill as much as you can to get that CYA down to the 40-50 ish range. You may need to do that in a series of smaller drain/fills, but that will work too. If you decide not to lower the CYA, keep in mind that you need to keep the chlorine at a minimum of 8 ppm to keep the algae away. You can get away with 5.5 for right now because the water is cold, but that won't last long, and since you just got it cleared up, I would hate for you to have to fight another outbreak this soon. Once your water temp gets above the mid 60s or so, you're going to need to get the chlorine up or the CYA down.

    Your TA is a little bit high but not high enough to worry with right now--when you start adjusting pH, the TA will adjust with it.

    Again, welcome to the forum and I look forward to seeing you around.

    Janet

  3. #3
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    Default Re: my first chemistry numbers

    thanks aylad.
    I guess it is time to head down and rent a pump to get rid of my cya infested water.
    I appreciate your help - the dizzle
    gunite inground 11.5k gal pool w/ attached 800 gal spa - Purex triton clean & clear plus 320 - Polaris 280 robot -
    Raypak 265b heater

  4. #4
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    Default Re: my first chemistry numbers

    Went down to home depot and rented a pump. I drained an impressive amount of water out of the pool. I then filled it up. it was about a 24 hour process. I cleaned the filters and installed a weir.
    I feel good!
    I just took my second set of chem numbers
    FC = 1.6
    cc = 0
    PH = 7.6
    TA = 120 ppm
    CYA = 50 ppm

    CYA is still a little on the high side, but I think I will have to deal with it. No more stabilized chlorine. Its all about the clorox from here on out. I will now do some reading to figure out how to lower TA a little. I am still not clear on how much bleach to add to get my FC levels up, I guess i will just add a couple of gallons and check it often.
    I must say I do like the taylor test kit, it is very easy to use and makes me feel Pro.

    thanks everyone-The Dizzle
    gunite inground 11.5k gal pool w/ attached 800 gal spa - Purex triton clean & clear plus 320 - Polaris 280 robot -
    Raypak 265b heater

  5. #5
    aylad's Avatar
    aylad is offline SuperMod Emeritus Burfle Ringer aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars aylad 4 stars
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    Default Re: my first chemistry numbers

    Hi Dizzle,

    A CYA of 50 is going to be MUCH easier to deal with than it was, so you'll find that all your hard work was worth it!! So now you need to up your chlorine just a tad, because with a CYA of 50 you want to keep your chlorine between 3 and 6 ppm at all times. I'm referencing this table that we use as a guideline for chlorine amounts for algae-free pools..... (better known as Ben's Best Guess Table)

    Stabilizer . . . . . . Min. FC . . . . Max FC . . . 'Shock' FC
    => 0 ppm . . . . . . . 1 ppm . . . . . 3 ppm . . . . 10 ppm
    => 10 - 20 ppm . . . . 2 ppm . . . . . 5 ppm . . . . 12 ppm
    => 30 - 50 ppm . . . . 3 ppm . . . . . 6 ppm . . . . 15 ppm
    => 60 - 90 ppm . . . . 5 ppm . . . . . 10 ppm . . .. 20 ppm
    => 100 - 200 ppm . . . 8 ppm . . . . . 15 ppm . . .. 25 ppm

    Note that since you're on the high end of the 30-50 range, I would encourage you to try to target the next higher chlorine ranges, just to make sure--meaning I wouldn't let mine drop below 5 ppm, and would probably target 5-8 ppm for daily chlorination. In an 11,500 gallon pool, each 3 1/2 cups of 6% bleach will raise your chlorine by 1 ppm, so you can use that as a guideline to figure out how much you need to add each day.

    Your alk isn't too bad at 120, so I wouldn't worry too much about adjusting it unless you're finding that your pH won't stay stable. If you need to adjust it, you can find the process stickied at the top of the "Alkalinity and calcium" part of the forum.

    Janet

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