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Thread: Replaced Liner KD Pool. Question about Balancing CYA

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    Replaced Liner KD Pool. Question about Balancing CYA

    Good Day,

    A friend of mine just replaced his Vinyl liner, and we filled it with water. It holds a mere 7,000 gallons.

    Right now the pH is at 6.8, Chlorine 1, Combined Chlorine 0, Alkalinity 50, CYA 0, and Calcium 110.


    Being this is basically a plastic pool, the calcium does not matter right?



    Everything is sparkling clear. Without doubt, the PH needs to be raised to around 7.4, which should also bump the Alkalinity a bit. Hence, it is my supposition the first thing to do is to raise the pH with some Soda Ash... and the Pool Calculator says to add 19oz (with TA of 50)... After doing this the pH should be reasonably well balanced around 7.4 AND the TA should increase to around 70.

    After this, it stands to reason that we will need to add about 32oz of Baking Soda to then raise the TA another 20 points bringing it to 90 stabilizing the pH.



    Now, it also makes sense we NEED to raise the CYA (AND the Free Chlorine), but we do NOT have any stabilizer. Why not just use Dichlor shock? I bought about 12 packets of it before I knew how much it messed with the CYA of my plaster pool. It seems now it would be ideal because it A) Dissolves very fast and B) Is almost a 1:1 in that if we raise the pool's chlorine to 20 ppm with it, the CYA should head to around 18... Let the chlorine fall to about 5 ppm then raise it to about 15 ppm.


    What do you think? Reasonable?

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    Re: Replaced Liner KD Pool. Question about Balancing CYA

    Whoa, it's late for me. Good to see you, NetWizz!

    Too many questions for me now, but I SO use dichlor. I have never purchased "stabilzer"/"conditioner", even when I started with brand new water after a new liner. Dichlor is a great way to slowly introduce CYA and FC at the same time. It will lower your pH a tad.

    However, low pH is scary, especially since you are at the lowest test range level for pH and it may well be lower than 6.8. I would suggest a combo approach but don't go overboard with the soda ash. Do you have borax instead?

    No worries on the CH. TA is the last thing to worry about. Easy to raise later, harder to lower.

    I hope that all makes sense and I did it right. I am tired!

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    Re: Replaced Liner KD Pool. Question about Balancing CYA

    Thanks Marian. I was looking at Pool Math and it actually says Dichlor will lower my pH even further, which is a bit scary.

    To be honest my comparitor goes down to 7.0 on the pH scale, and I am guessing 6.8.


    I don't have any Borax, but I have a whole 5 Gal Blucket of Soda Ash the pool store sold me for my plaster pool ... Turns out my pool consumes acid NOT soda ash (that was another waste of money), but it may help my friend get his pH up.

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    Re: Replaced Liner KD Pool. Question about Balancing CYA

    Arg! I was editing my post as you were responding.... Like I said, I am brain-tired. I was just so happy to see your name posting!

    You are right about dichlor lowering the pH, but it's not a huge effect.

    if you have soda ash on hand, go for it.

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    Re: Replaced Liner KD Pool. Question about Balancing CYA

    Using dichlor to chlorinate and raise CYA is fine as long as you know exactly what to expect from it. Normally I wouldn't recommend it for someone without a lot of experience, but you do seem to have a good handle on using pool math to know what will happen. One thing, I wouldn't bring the FC to 20, keep it under 10 until the CYA reads at least 30.

    As for soda ash, this sounds like a good time to use it since it will raise both pH and TA. Just be aware that it could temporarily cloud the pool if you add a large amount, add it slowly.
    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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    Re: Replaced Liner KD Pool. Question about Balancing CYA

    Double ditto what donldson just posted.

    Dichlor has multiple effects on pool water and I would NEVER suggest it for inexperienced or even moderately new users. Frankly it's really quite easy to just go buy some CYA and balance your pool.

    Overshooting and undershooting dosages is a common problem and that you are doing it for a "friend of mine" increases the chances even greater. Dichlor is a somewhat complicated solution to an easy problem.

    NETwizz, you certainly do as you wish, but, newbies, please keep your dosages simple and avoid dichlor.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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