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Thread: Soft water - SWCG - Pool Chemistry

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    Soft water - SWCG - Pool Chemistry

    Okay, so I have been following this website for a while and can I say that as a new pool owner, I am very appreciative of all the information that is presented here. I have a question about softening my fill water before it goes into the pool because I am using a well and it comes out at almost 1500 ppm of calcium hardness. I have a way that I can fill it with soft water which will then convert the calcium into sodium (but not sodium chloride) and I am wondering if I convert to a SWCG pool if this is going to affect the sodium chloride levels that I have to keep for the SWCG to work properly.

    My fill water comes out at a

    pH of 6.8-7
    TA of roughly 200
    Calcium of 1500

    I just recently drained half of my pool because my CYA had reached astronomical numbers from the pucks that everyone told me to use until I found this forum. So, I have done exactly what BBB recommends as far as shocking the pool, adding CYA back in to now a number of 60 and keep my chlorine at roughly 10% of the CYA level after shocking.

    I am worried about scaling issues though and now want to drain the whole thing, fill up with soft water and add in with the hose water from the well to add back in calcium as needed (much easier to add, than to get rid of it).

    I guess mostly I am wondering if anyone has every experimented with soft water in their pool and if it had any effect on chlorine levels, pH levels (which I am told the water comes out at roughly the same pH that it goes in at), TA levels and any other information that anyone can add would be great.

    My pool is a 35,000 gallon plaster pool and am also wondering what SWCG everyone recommends. Thank you in advance.

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    JasonLion's Avatar
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    Re: Soft water - SWCG - Pool Chemistry

    Using softened water works very well as long as you adjust the CH level as needed after filling. Better yet, fill with a mixture of softened water and plain water to get to the desired CH level. The one thing to keep in mind is that the water softener will add a lot of salt. Generally the salt level will still be alright, but if you top off the pool with softened water and have lots of evaporation there is some chance that the salt level could eventually get too high. High salt levels can also be an issue for some brands of SWG.
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    frogabog's Avatar
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    Re: Soft water - SWCG - Pool Chemistry

    FWIW, my pool is all soft... about 4ppm CH. It seems to function and operate about the same as everyone else's in regards to pH, TA, FC, and of course, CYA.

    Only difference is the possibility that the SWG is functioning at a low salt level, happily. I've got 1850ppm. Well under the recommended salt level and my SWG seems to hum along fine. Still waiting to get that one figured out, hopefully blessed by a ChemGeek Epic Post "~}
    Where kids swim in 54 degree water, turn blue, and giggle happily cuz they got a POOL!
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    Re: Soft water - SWCG - Pool Chemistry

    I was under the impression that sodium chloride that the swcg needs and the sodium ions are totally different things. Also, would it be better to use potassium instead of sodium? What is the recommended potassium level in a pool?

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    JasonLion's Avatar
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    Re: Soft water - SWCG - Pool Chemistry

    It is the same salt in either case. Salt used by a SWG or a water softener is made up of two components, the first is either sodium or potassium and the second is chloride. In a water softener it is the sodium/potassium that does the work, while in a swimming pool SWG it is the chloride that does the work. Regardless, both always appear together in the water.

    The SWG doesn't care if you use sodium chloride or potassium chloride, however potassium chloride is more expensive and you need to use more to get the same effect, so we recommend using sodium chloride. The correct level depends on what brand of SWG you have. Levels around 3,200 are common, but it varies somewhat from brand to brand.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    Re: Soft water - SWCG - Pool Chemistry

    I understand that the water softener uses sodium, but what is the end result after it is exchanged for the calcium and magnesium?

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    Re: Soft water - SWCG - Pool Chemistry

    The calcium and magnesium bind to the water softener (ion exchange resin) and sodium ions are released into the water. For every one calcium or magnesium, two sodium are released.
    16,000 gallon outdoor in-ground 16'x32' plaster pool; Pentair Intelliflo VF pump; Pentair IntelliTouch i9+3s control system; Jandy CL-340 square foot cartridge filter
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    Re: Soft water - SWCG - Pool Chemistry

    Chem geek - can the swcg use this sodium or it needs sodium chloride?

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    JasonLion's Avatar
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    Re: Soft water - SWCG - Pool Chemistry

    The SWG uses chloride. When you add salt to the water softener it adds both sodium and chloride. The chloride will also be in the water coming out of the water softener along with the sodium, and the SWG can work with that chloride (if the level is appropriate).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
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    bobodaclown's Avatar
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    Re: Soft water - SWCG - Pool Chemistry

    Basic entry model SWCG no bells or whistles Compupool CPSC48, can be bought/delivered for $750.
    17K Kidney Shaped Pool Concrete (Diamond Bright) Pool, 3/4 hp 2 speed 115V Sta-rite Duraglas PEA5D-180L/P2R5D-181L (Impeller C105-92PS Diffuser C1-216P), 1.5 piping, Pentair CC100 Filter , Heat Siphon 100K BTU Heat Pump Pool Heater, Flow meter Blue White Flowmeter Model No. F-30150P, Hayward Astrolight SP0581N, SWCG CalimarTitanium Edition TE45 , Dolphin Nautilus Plus with CleverClean, Lakeland Florida

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    Re: Soft water - SWCG - Pool Chemistry

    When the calcium and magnesium is exchanged for sodium, calcium and magnesium chloride go down the drain so there is no chloride with the sodium from my understanding. I guess my main concern is that the extra salt in the water (1500 from water and softener and 3500 sodium chloride for swcg) isn't going to pose any other problems in my pool. Do you know the effects on swcg and/or the plaster pool itself? Thank you.

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    JasonLion's Avatar
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    Re: Soft water - SWCG - Pool Chemistry

    Salt levels up to 5000 are just fine with nearly all pools. There is a small risk to natural stone work, especially softer kinds of stone. Every now and then you also run into some builder cutting corners and using inferior grades of nuts/bolts/screws which are sensitive to salt, but that has gotten to be very rare.

    Some chloride always makes its way into the water from the water softener, even though much of it is rinsed away. The salt test that measured the 1500 level from the softener is measuring chloride levels.
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    Re: Soft water - SWCG - Pool Chemistry

    The calcium level is 1500 so I was counting on the sodium being at least that much when I fill with soft water. What salt water generator do you recommend?

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