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Thread: High Chemical Hardness

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    High Chemical Hardness

    I had my pool resurfaced with pebbles in July and am very happy with the results. I decided to actually take care of the pool this time and turned to Trouble Free Pool. I use a SWG which I love and added borates which gave me a soft feel and super clear water.

    The problem I'm having is with acid demand and the problems it brings. Both TA and CH tend to climb out of their range. I built the three headed sprinkler I found on your site and have used it and acid to lower the TA. You will notice from the numbers below that I need to do it again.

    The Chemical Hardness in the water started at 220 and has climbed to 475. The CSI index is -0.47. Everything I read says I need to remove about a third of the water from my pool and refill. Since that will change the levels of almost everything in the pool I want to be sure that is the only option.

    Thanks for your help and great site.

    FC: 6
    CC: 0
    PH: 7.5 today 8 in two days
    TA: 100
    CH: 475
    CYA: 80
    Borates: 50
    Pool size 8,500 gal., built in 1995 resurfaced in 2012
    pebble surface
    SWG, Solar heated
    Taylor K-2006 test kit

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    dmanb2b's Avatar
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    Re: High Chemical Hardness

    Welcome to TFP

    Take a read through the below post...very similar to your situation. Only way to lower CH is partial drain and fill or reverse osmosis treatment, but your CH is not high enought to warrant the cost of a RO treatment IMO.

    fighting-scale-and-high-ph-in-pebbletec-swcg-pool-t54118.html
    24'x52" AGP (13,500 Gallons), Intex SWG, (2)Solar Bear 4x20 panels, Hayward S220T Filter, 1/2hp Pentair Superflo

    Pool School, TFTestKits, Pool Calculator

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    Join Date
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    Re: High Chemical Hardness

    I'm not sure how you are getting a CSI of -.47 with those numbers. Salt and temp have some bearing on the CSI and you did not list those. In your situation, the calcium is only helping to make the CSI +. You will most likely have to live with your pH swinging rapidly for a year, then it should start to slow down. Hopefully the pH swing will slow down with the cold water this winter.
    16k gal plaster with raised spa, Jandy DEV60 filter, 2 HP 2-speed SHPF Jandy Stealth pump
    Hayward Aqua Rite T-15 SWCG, Jandy LXi 400k BTU NG heater, 350 sq.ft. of Sun Star solar panels, TF-100 Test Kit, Dolphin s300i Cleaner
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    UnderWaterVanya's Avatar
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    Re: High Chemical Hardness

    Quote Originally Posted by ping
    I'm not sure how you are getting a CSI of -.47 with those numbers. Salt and temp have some bearing on the CSI and you did not list those. In your situation, the calcium is only helping to make the CSI +. You will most likely have to live with your pH swinging rapidly for a year, then it should start to slow down. Hopefully the pH swing will slow down with the cold water this winter.
    Just for grins I added all this into Poolcalculator and if I set the salt 3500ppm and the temp to 41 degrees I can get the same CSI. With salt at 4500ppm I get this result at 44 degrees. With salt at 3000ppm I need the temp to be 38 degrees. I'm not sure where the OP is but these seem pretty crazy temps to me.

    I did notice that at a pH of 8 - the CSI index was better with the low temps - as the temp climbed the index eventually could go too far and indicate scaling potential.
    Inlaws Pool Boy since June 14th 2012, Pool built ~ 2003, In-Ground, 16'x32'
    13500 gal, Vinyl Liner, Fiberglass Slide, TF-100 Test Kit, Hayward 210T
    sand filter, A.O. Smith 1.5HP main pump motor (C48L2N134C1),
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    Re: High Chemical Hardness

    I adjusted the PH down to 7.6 and took a new set of readings.

    FC: 6
    CC: 0
    PH: 7.6
    TA: 75 (back into range)
    CH: 425 (still too high)
    CYA: 80
    Borates: 50
    W/T: 85'
    Salt: 3000

    I used the Taylor Watergram Calculator and got a CSI of 0.2 while The Pool Calculator says 0.28 and recommends replacing 29% of my pool water with 0 CH water. My tap water has a CH of 125 so I may be looking at replacing half the water in my pool. I'm about ready to turn off the solar heat for the winter. Lower water temperatures (60'f) would lower the CSI index to 0.0 which I think is the goal.

    Question: Can I hold off replacing the pool water, which is expensive, by lowering the water temperature. We get lots of free water during the rainy season. I'm quite willing to replace the water now if there is a good chance of damage to the pool surface or equipment.

    Thanks
    Pool size 8,500 gal., built in 1995 resurfaced in 2012
    pebble surface
    SWG, Solar heated
    Taylor K-2006 test kit

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    duraleigh's Avatar
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    Re: High Chemical Hardness

    If that was my pool I would do absolutely nothing but lower the pH down to around 7.2 - 7.4 and monitor it to keep it there. The CSI is seldom useful to most pool owners and if you simply keep your parameters within the guidelines we suggest (you're close already, and you say you can dilute your CH by rainwater) then you will never have a problem.

    You don't say where you live but I assume you know what "lots of freewater" is to reduce your CH to below 400
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
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