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Thread: Chemistry advice

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    AV8TOR's Avatar
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    Dec 2008
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    Chemistry advice

    OK my TF-100 kit came today (thanks Dave for the speedy order ). We just bought this home that came with a pool and although it looks awesome I would like to get your opinion. I always knew that the FC was high as it pegged my 5 ppm test kits. Turns out 32 drops to turn clear 16ppm with no CC (makes the OTO test useless). My CYC was at 100. So at 100 my FC should be between 7 and 12 (non SWG pools) I know for a fact that the pool service from the previous owner used 3” tablets. I have not added any chlorine. The feeder is now dry and just waiting for it to burn off. I plan on using bleach with the occasional tablet when we are gone for some time. So with a CYA of 100 would you drain down the pool some and re-fill to dilute the CYA or leave it at 100? If so how much down would you take it. My pool is approximately 12000 gallons.
    16,000 gal IG Double Roman Plaster Pool (16yrs - plaster redone 2014)
    Pentair FNS-48 DE filter with WhisperFlo 2HP single speed pump
    Polaris 280 robot
    BBB all the way and tested with a TF100 kit
    Pool Calc user

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    JasonLion's Avatar
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    Re: Chemistry advice

    Nearly all of the CYA tests will read values over 100 as if they were 100, so it is difficult to know what your current CYA level really is. You can do the CYA test with a sample that is half pool water and half tap water and then multiply the result by two to get an approximate CYA level between 100 and 200, but this will not be very accurate.

    You should lower your CYA level down to 80 or lower. If you don't have a SWG then 50 is a better target, though you can get away with 80 if replacement water is difficult to come by or too expensive. If your level really is 100 right now, lowering it to 80 means a 20% water replacement and lowering it to 50 means a 50% water replacement. If your current CYA level is higher you will need to replace more water.

    If the water is cold right now, below 50 degrees, this can be put off till spring.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    duraleigh's Avatar
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    Re: Chemistry advice

    Hey,

    Very revealing test results. Do not feel like the "Lone Ranger"....many folks take over pools that have been over-saturated with CYA and FC much like yours.

    What I suggest doing to your pool depends on how you intend to treat it the rest of the 0ff-season. My assumption is you are finished swimming in your climate. If that's true, I'd leave your pool alone and allow the FC and CYA to come down on their own.

    You will probably see the CYA stay pretty stable over the winter....(I'd check it once each month at the most) Rainwater will eventuall dilute it down some but I would not drain it this winter. When I got ready to clean up and open up the pool next spring, I would adjust it to 50 without an SWG and no more than 80 with an SWG. You may be over 100 but I think you can get thru the winter if you choose.

    Your FC will come down on it's own over the next couple of weeks. Given your high CYA, I think I would try to keep a little FC in the pool even thru the winter.....say around 5ppm. Again, you'll need to adjust it when you open in the Spring but it will be ok since you're not swimming now.

    Reread some of the first basic aticles in "Pool School". They'll tell you target numbers to shoot for on all your tests. You can get them inline now (and most will stay there except for FC) or you can be a little casual about them 'til you open up.

    Posting your pH and Calcium and Alk will help complete the picture.


    Oops, now see Jason posted ahead of me saying essentially the same thing.

    PS - your OTO test will be viable again once your CYA is down to around 50 and you then keep your FC around 3-4ppm.
    Dave S. - Forum owner
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    AV8TOR's Avatar
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    Re: Chemistry advice

    Thanks guys - I will wait then to dilute it when the warmer weather arrives. The pH was 7.5 Alk 90 and I did not have time for the calcium test.
    I just ran home lunchtime to play with my new test kit
    16,000 gal IG Double Roman Plaster Pool (16yrs - plaster redone 2014)
    Pentair FNS-48 DE filter with WhisperFlo 2HP single speed pump
    Polaris 280 robot
    BBB all the way and tested with a TF100 kit
    Pool Calc user

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