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Thread: Pool store says it's fine, looking for other opinions on chemistry

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    Pool store says it's fine, looking for other opinions on chemistry

    I have a newer pool and I need some opinions on water chemistry. My TA is low and pH is high. The pool store tells me that no additives are necessary and everything is exactly where it should be for a new pool. What are your thoughts? I'm nervous about the pH. TF-100 test kit is being used and I'm also taking samples to the pool store. Pool water clarity is excellent.

    Test results:

    FC: 3ppm
    CC: 0.5 ppm
    TA: 80
    pH: 8.2
    CH: 325

    Pool Details:

    Pebblesheen, SWG, large sun deck with bubbler, small waterfall, 10,600 gallons

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    Mod Squad JVTrain's Avatar
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    Re: Pool store says it's fine, looking for other opinions on chemistry

    pH is definitely high. Recommended levels are 7.5-7.8

    TA is OK, but could be lower depending on how your pH behaves. With the pH currently being high, does that happen often? The reason slightly lower TA is recommended for SWCG pool is that they create more aeration and can drive pH up faster, so lower TA is better.

    We can't tell if your FC is appropriate without a CYA level.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
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    Re: Pool store says it's fine, looking for other opinions on chemistry

    CYA was at 60, but I'm still perfecting that test...

    The pH has been high since I took over the pool from the builder. The builder was maintaining the pool for the first two months, I've been maintaining it for about 6 weeks.

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    Mod Squad JVTrain's Avatar
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    Re: Pool store says it's fine, looking for other opinions on chemistry

    For an SWCG system, that FC level is OK. I'd try to maintain more like 4 FC with the SWCG at that CYA level. I hope you're familiar with the Chlorine/CYA Chart. Also, being in Florida you might be more efficient at a slightly higher CYA of 70. The 0.5 CC is a bit concerning, but not a red flag. Is the water clear? Any visible signs of algae?

    Get that pH down to 7.5 using preferably muriatic acid. Use Pool Math to calculate how much. Be sure to put in your current TA value in Pool Math to get an accurate volume. If you're unsure if you've done the Pool Math right, post what your planning on adding first. This will also have the effect of lowering your TA.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
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    Re: Pool store says it's fine, looking for other opinions on chemistry

    The water is super clear. Looks great.

    Pool math tells me to add 15 oz of 31.45% muriatic acid, or 20 oz of dry acid. Sound right?

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    Mod Squad JVTrain's Avatar
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    Re: Pool store says it's fine, looking for other opinions on chemistry

    Looks correct. 2 cups or 1 pint of acid (16 oz) should get you there. Make sure water is circulating when you add and if you want to check pH after, wait 30 minutes while circulating before testing again. It's just fine if it happens to go down to 7.4.
    Joel - TFP Moderator - Minnesota - **Become a TFP Supporter!** Helpful Links: ABCs of Pool Water Chemistry - SLAM Procedure - Chlorine/CYA Chart
    40x20 Pool: 32K Gallons * Vinyl * Bleach Chlorination * Hayward S270T Sand Filter * Pentair SuperFlo 1 HP * Teledyne/Laars Heater * AquaVac Tigershark * TF-100 w/ SpeedStir
    Isolated Spa - 345 Gallons

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    Re: Pool store says it's fine, looking for other opinions on chemistry

    How often do run the bubblers & waterfall?

    One thing you have to know is that your TA will decrease with acid and aeration. Your SWG is providing some and your waterfall and bubblers are providing A LOT. The aeration raises your pH by releasing dissolved CO2 in the water.

    Since TA is related to the pH buffeting capacity of your pool water, one way to see it's affect is to do the acid-demand test. Not sure if the TF100 has the reagent for acid demand but it is nothing more than a normalized solution of HCl. You add it drop wise to your test tube after adding the pH indicator and you count how many drops it takes to get you from where you are to the pH you want to be at. If your TA is high, it takes more drops of the acid demand reagent to get to a lower pH.

    Your current TA value is fine for an SWG pool. But you so need to keep an eye on it and adjust your waterfall and bubbler use as needed. If it gets too low, the nice part is you can run to the supermarket and buy cheap old reliable baking soda to raise it up.



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    Re: Pool store says it's fine, looking for other opinions on chemistry

    Quote Originally Posted by SunnyOptimism View Post
    One thing you have to know is that your TA will decrease with acid and aeration. Your SWG is providing some and your waterfall and bubblers are providing A LOT. The aeration raises your pH by releasing dissolved CO2 in the water.
    TA only decreases with acid additions which is what comes next since the aeration will raise the pH.
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    Pool store says it's fine, looking for other opinions on chemistry

    Quote Originally Posted by easttn View Post
    TA only decreases with acid additions which is what comes next since the aeration will raise the pH.
    Sorry if my original statement was confusing. Yes, acid additions lowers the TA and then aeration (in whatever form it takes) is what raises the pH back up without increasing TA. I should have written "acid/aeration" to denote it as a process.

    Tapping away on a smartphone all day gets a bit tiresome....



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