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Thread: Help balancing TA and CSI

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    Help balancing TA and CSI

    Here are my latest numbers:

    FC = 5
    PH = 7.2
    TA = 50
    Ch = 280
    CYA = 20
    Salt = 3200
    Borate = 50
    Temp = 72 and rising

    Historically I've tried to keep my TA to the low side as I was seeing PH rise due to running the liquidator. This weekend I liquidated the liquidator and replaced it with a salt system (salt currently at 3800, but I think that it hasn't fully dissolved). When I ran my numbers above through the pool calculator the CSI showed -0.93

    Clearly I need to bring the PH, TA and CYA up. I now have a sock full of CYA in the skimmer. I was thinking to bring the TA up to 70, but then when I run through pool calculator it appears that I would need to have the PH up at 8.1 before it would show as balanced. If I bring the TA up to 100 the calculator shows that I could go down as far at 7.7 and stay balanced. Suggestions?
    18,000 gallon 17 x 35 in-ground diamond brite, Fafco solar, SWG, Barracuda G3, well pump - Biscayne Aquifer CH=250

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    Re: Help balancing TA and CSI

    I'm going to toss this out here.

    You've got your CYA issue covered which is good. That leaves your pH and your TA to deal with. What I would probably do is go ahead and try to effect some change in your TA with baking soda. You might shoot for a TA of 70 to start. Retest TA and pH and see where that gets you.

    The main problem that you are going to have here is that you have 50 ppm of borates in your water. So instead of one buffer system working against changes in pH, you essentially have two buffer systems that work independently of one another. I think that this is going to make adjusting these two things much more difficult for you. At least, that's the way that I understand it and why it is so important to make sure that you get the TA right where you want it before adding the borates.

    Hopefully, a guru can suggest additional things for you here. I'm not sure how to get around the borates being in your water to make the changes that you need.
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    polyvue's Avatar
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    Re: Help balancing TA and CSI

    I think you could bring your TA up to 90 or so and let the rising temperature take care of the pH difference.
    14,555 gal in-ground 16'x29' white plaster Pool w/spa (2007); Goldline Aqua Logic AQL-PS-8 control w/Aqua Cell 15 Salt Water Chlorination (SWCG); Hayward TriStar 1HP (1.85 SF) main / 1.5HP (1.60 SF) spa pumps; Hayward Swimclear cart filter C4025, ColorLogic LED lights; Tankless SP-18-4 electric heater; Polaris 280 cleaner.
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    JasonLion's Avatar
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    Re: Help balancing TA and CSI

    Borates at 50 is good and will not lead to any special challenges in this situation. The quantity of chemical needed to raise the PH will be more than it would be without the borates, which is a good thing.

    Both PH and TA are too low, though neither one by very much. You want to raise PH to at least 7.4, and TA to around 70. There are several ways to do that. I suggest using about 20 oz of soda ash/washing soda and 32 oz of baking soda, but you could use a combination of borax and baking soda instead.

    Raise CYA to between 70 and 80.

    Your current CSI is too low. The changes I suggest above will take care of most of the adjustment you need. To go the last little bit I suggest raising the CH level to around 350-400. That will leave you with CSI around -0.3 or -0.4, which is a good place to be. You don't generally want CSI right at zero, it can be allowed to move around a fair bit. On average you want CSI to be below zero. PH tends to go up with a SWG, not down, and the CSI is higher inside the SWG and heater (if you have one).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Help balancing TA and CSI

    Quote Originally Posted by JasonLion
    Borates at 50 is good and will not lead to any special challenges in this situation. The quantity of chemical needed to raise the PH will be more than it would be without the borates, which is a good thing.
    I understand what you're saying re:Borates. That's why I put them in (plus the feel, which we *think* is better)

    Interesting - I hadn't considered changing CH to compensate... If I understand you correctly, by raising the CH I should be essentially buying myself a window where I can adjust the PH and TA around to get them where they give good CSI numbers (broader range). Am I on the right track?

    Thanks Jason!
    18,000 gallon 17 x 35 in-ground diamond brite, Fafco solar, SWG, Barracuda G3, well pump - Biscayne Aquifer CH=250

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    JasonLion's Avatar
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    Re: Help balancing TA and CSI

    There are quite a number of factors that affect CSI, which is one of many reasons we tend to tell people to not even try to think about CSI, and just keep things in the recommended range. In your situation several of the factors are forced to be in specific ranges for reasons having nothing to do with CSI. For example, TA should be 60 to 70 because lower means PH swings too easily and higher means PH rises too quickly. Likewise, PH, borates, salt, and CYA are all constrained by a variety of factors. That leaves CH as the primary number that you can vary to adjust where you sit in the CSI range, because CH has the fewest non-CSI reasons to be at any particular level.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Help balancing TA and CSI

    CSI isn't the only consideration. You want your TA and pH to be in a place where they are not constantly dragging on each other. What I would do is fiddle the TA/pH as Jason suggested, make sure the new levels are reasonably stable (where "reasonably" is something only you can define), and only then see about moving the CH to a level where the CSI is in the right target range.
    --paulr
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    Re: Help balancing TA and CSI

    Adding CYA will raise your TA slightly. I would wait for the CYA to dissolve and re-measure the TA before adding baking soda.
    7,500 gal, IG pool, L shape 22' x 15', 1.5 hp pump, cartridge filter, AquaPlus SWG/Controller, Pebble-Tec liner.

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