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Thread: Need to lower TA and raise CYA a bit

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    minxcal's Avatar
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    Need to lower TA and raise CYA a bit

    Hello!

    I've been working on lowering TA since pool was installed. Backwashed yesterday which meant I needed to add even more water than I already needed to add, so added some yesterday, and then it rained and it came back up from 120. Trying to hit the target!

    Current readings:
    FC - 4
    CC - 0
    pH - between 7.5 - 7.8, so go w/ 7.6
    TA - 140
    CYA - 40

    With all of that yesterday, with today's test, TA crept up 20, and with the rain and the top off, CYA is down 15, pH came up since last addition of acid, so now I also need to add a bit of stabilizer. I know CYA will lower pH, but will it also lower TA? If not, should I just add the CYA, wait, and add acid for TA when it's all done and pH is back up from stabilizer addition or add acid then just wait a couple of hours and add CYA?
    17' x 30' plaster pool, Intellipro Variable Speed pump, filter that's about to be replaced, 1 skimmer and 2 returns, and that's about all I know about this pool!
    4' ledge all the way around, deep "scoop" about 9' deep - NO DIVING!

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    Re: Need to lower TA and raise CYA a bit

    CYA doesn't affect pH.

    With a CYA of 40, you should be fine. Why are you trying to raise CYA?
    8,000 gallon, in ground, fiberglass pool with a cartridge filter.

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    Re: Need to lower TA and raise CYA a bit

    disregard.....sorry

    you're using a SWG, so that's why you want to raise CYA to 70 - 80.

    How many gallons is your pool?


    Have you used the poolcalculator?:

    calc.html
    8,000 gallon, in ground, fiberglass pool with a cartridge filter.

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    minxcal's Avatar
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    Re: Need to lower TA and raise CYA a bit

    According to the pool calculator, CYA lowers pH, quite a bit actually:



    I have a SWG. CYA if 40 is not near enough.
    17' x 30' plaster pool, Intellipro Variable Speed pump, filter that's about to be replaced, 1 skimmer and 2 returns, and that's about all I know about this pool!
    4' ledge all the way around, deep "scoop" about 9' deep - NO DIVING!

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    minxcal's Avatar
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    Re: Need to lower TA and raise CYA a bit

    I use the pool calculator almost daily. I just need to know what order to attack things.
    17' x 30' plaster pool, Intellipro Variable Speed pump, filter that's about to be replaced, 1 skimmer and 2 returns, and that's about all I know about this pool!
    4' ledge all the way around, deep "scoop" about 9' deep - NO DIVING!

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    Re: Need to lower TA and raise CYA a bit

    Quote Originally Posted by minxcal
    According to the pool calculator, CYA lowers pH, quite a bit actually:



    I have a SWG. CYA if 40 is not near enough.

    Oops. Open mouth, insert foot.


    Learn something new everyday.


    If the CYA lowers pH, then it should also lower TA, right?
    8,000 gallon, in ground, fiberglass pool with a cartridge filter.

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    minxcal's Avatar
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    Re: Need to lower TA and raise CYA a bit

    Ha! yeah, me too! I love this forum. Studied up for about 6 weeks before I ever even posted anything cause I didn't want to be told to read Pool School - I alredy did it - many times! I think I'm going w/ adding acid, bringing pH back up, then add CYA in a sock at the end of the day. Sounds like a plan to me!
    17' x 30' plaster pool, Intellipro Variable Speed pump, filter that's about to be replaced, 1 skimmer and 2 returns, and that's about all I know about this pool!
    4' ledge all the way around, deep "scoop" about 9' deep - NO DIVING!

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    Smykowski's Avatar
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    Re: Need to lower TA and raise CYA a bit

    Quote Originally Posted by GuinnessPhish

    If the CYA lowers pH, then it should also lower TA, right?
    Yes. The faster way to do it is to lower pH with MA, then aerate. However, since CYA is acidic, the same process occurs. (But pH drop is a byproduct of CYA addition. Don't lower pH with CYA exclusively!!)
    33' round, 23,000 gal AG vinyl , 1HP 2spd PowerFlo Matrix downsized with 3/4HP impeller (X2), Hayward S180T 150# sand filter (X2), Hayward H250 NG heater Pool Store year 1 - $850 for 2 months; Pool Store year 2 - $440 for 2 months, TFPC year 1 - $170 for 4 months; TFPC year 2 - $95 for 4.5 months
    The most important article on this site - The ABCs of Pool Water Chemistry

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    linen's Avatar
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    Re: Need to lower TA and raise CYA a bit

    Adding that much cya (32 oz) will only lower your TA by about ~10 ppm (depends on a number of other things) and it will drop you ph less than the calculator shows since your TA is a little higher. In the end you might not even notice the ph drop from the cya since it dissolves slowly and your ph will be creeping up.

    I would ignore the ph effects of the cya for now (assuming granular) and deal with getting your TA down independently.
    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.

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