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Thread: Odd well water

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    Join Date
    Feb 2009
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    Paradise (Hampstead, NC)
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    Odd well water

    Finally got a new pool installed after 3 years. (it's complicated; I'll have a complete update in construction later.) I knew that my well water was hard, the aquifer lies under a limestone cap. But fresh water from the well read a TA of 210 with a ph of 6.8. I would have expected a much higher ph reading. I do use the TF 100. Dissolved iron was horrible, I probably could have used a giant magnet to clear it! It didn't drop out with sunlight; raising the ph and adding chlorine did start the process. I supplemented the sand with fiber and used a metal flocculent to get it to drop. Most of it is gone after many scrubbings, vacuumings and backwashes. Why would there be such a divergence with the TA and ph? Doing the CH test, is the change point when the pink turns clear? (260) Or is there a point when it actually turns blue? Being slightly color blind makes titration readings a challenge. I quit at 32 drops.
    16X32 AB, Pentair SD filter, 3/4hp Pentair Optiflo, CircuPool RJ30+ swg, TF 100

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    JoyfulNoise's Avatar
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    May 2015
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    Tucson, AZ
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    Re: Odd well water

    The ground water, as you say, is sealed under a limestone cap, therefore there is no gas exchange. Once the water is brought to the surface and the dissolved CO2 is allowed exchange/escape, the pH will rise. It's like a can of seltzer water, the pH is very low but the alkalinity is extremely high. As soon as you pop open the can, the CO2 bubbles away and the pH starts to rise.

    As for the CH test, the transition is from pinkish-red to baby blue. It should not go clear. If you need to, you can add an extra drop or two of the R-0011L indicator dye. Dissolved iron in the form of the ferric ion (Fe2+) can interfere with the test of the concentration is high enough.
    Matt
    16k IG PebbleTec pool, 650gal spa, spillway and waterfall, 3HP IntelliFlo VS / 1.5HP WhisperFlo, Pentair QuadDE-100 filter, IC40 SWCG, MasterTemp 400k BTU/hr NG heater, KreepyKrauly suction-side cleaner Dolphin S300i robot, EasyTouch controls, city water, K-1001, K-2006 and K-1766 test kits, Mannitol test for borates

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    Feb 2009
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    Re: Odd well water

    I retested with 7 drops of the R-0011L and the blue changed at 22 drops. I've also been topping off with softened water. Old hoses tend to spring leaks. So things are within range there. Now to work on the TA.
    16X32 AB, Pentair SD filter, 3/4hp Pentair Optiflo, CircuPool RJ30+ swg, TF 100

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