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Thread: Calcium Hardness question

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    Join Date
    May 2012
    Location
    Lexington, SC
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    125

    Calcium Hardness question

    First off let me say that I'm ordering my test kit today. The numbers I'm posting are from Leslie's 2 days ago. I know that they will have changed since then but my main concern at this very moment is calcium hardness. Today I'm planning on taking a sample to another pool store to compare their results of the calcium hardness test (partly for fun - it's fun to see the difference, and partly because if it's in the same range of Leslie's, then I know I really do need to work on it).

    FC: +5
    TC: +5
    pH: 7.6
    TA: 90
    CYA: 48
    CH: 130

    You can see why I'm wanting to take care of calcium hardness right now. My other problem is we keep noticing a slight algae problem, but I'm sure that's just from not shocking long enough. I'll post questions on that soon. Leslie's recommends almost 18 1/2 pounds of Hardness Plus. I saw in Pool School Hardness Plus was one of the things listed to use...but I just wanted to make sure that is okay to purchase and there's not something a little simpler to purchase to use. I see on poolcalculator.com it says to use either calcium chloride or calcium chloride dihydrate...I don't know what those are or where to find them (help?).

    Another sidenote: We resurfaced our pool almost exactly 12 months ago now. I'm surprised that our CH has dropped like it has. A few weeks ago I tested my water at Leslie's and got a reading that was of no concern (don't remember...I'm sure I have the results somewhere but can't access right now). Is it possible the lady just did the test wrong? Should I wait until I get my test kit or do it because of what can happen if you have low CH? Just concerned about our new pool finish.

    Sorry so long. Thanks for the help!
    13,500 gallons
    Sand filter
    IG
    Plaster
    TF-100

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    JasonLion's Avatar
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    May 2007
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    Re: Calcium Hardness question

    It is certainly possible for pool stores to get test results wildly wrong. If your new test kit is arriving soon, I would wait for results from it before adjusting. If CH is actually around 130, you will certainly want to raise it.

    Did you winterize the pool? Refilling in the spring lowers the CH level.

    The easiest way to find calcium chloride is from a pool store. They will call it something like calcium hardness increaser. It can also be gotten from concrete supply places (used to accelerate curing of concrete), and as an ice melter (though not so easily this time of year).
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    May 2012
    Location
    Lexington, SC
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    Re: Calcium Hardness question

    We did actually winterize the pool...but get this...I just found my last test results from Leslie's, and this was just from a few weeks ago, and the CH was 220. It's rained, but in my opinion not enough to bring it down to 130. Does that make sense or does it just seem more plausible that the lady made an error in the results? Just ordered my test kit, and I'm in SC, so I have a good chance of getting it tomorrow. I could use my Jacks Magic one. I just don't like it. So sad. Spent a pretty penny on that kit too.
    13,500 gallons
    Sand filter
    IG
    Plaster
    TF-100

  4. Back To Top    #4

    Join Date
    Mar 2011
    Location
    Houston, Texas
    Posts
    413

    Re: Calcium Hardness question

    The pool stores here in Houston consistently tested my CH anywhere from 100 to 180 ppm low vs. my TFP-100 test kit. I was getting 500 ppm and they were getting 320 to 400.
    9,200 gal. Gunite Luna Quartz French Grey pool with spill over spa, two fountains on tanning ledge (rarely used)
    Pentair Whisperflo 2HP, Pentair CCP Cartridge 420 Sq. Ft., Polaris 280 with booster pump
    Pentair EasyTouch 4, RayPak LoNox 266k Natural Gas heater, Aqua Rite SWCG T Cell 9, Borates, TF-100 test kit

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    JasonLion's Avatar
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    May 2007
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    Silver Spring, MD
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    Re: Calcium Hardness question

    That sounds like testing errors at the pool store, common enough.
    19K gal, vinyl, 1/2 HP WhisperFlo pump, 200 sqft cartridge filter, AutoPilot Digital SWG, Dolphin Dynamic cleaning robot
    Creator of PoolMath and Pool Calculator. Other handy links: Support this site, TF Test Kits, Pool School

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    May 2012
    Location
    Lexington, SC
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    Re: Calcium Hardness question

    So just for kicks I went to Griffin Pools and had them test my water while I'm waiting for my test kit to arrive. They are the reason I started going to Leslie's. Now I'm not so sure I trust Leslie's, and I still don't trust Griffin!

    CYA: 90
    FC: 3.7
    pH: 8.1
    TA: 102
    Adjusted TA: 75***
    Total Hardness: 313***

    So what is the difference between Total Alkalinity and Adjusted Total Alkalinity? Which one matters? And what is Total Hardness? Is that CH? If it is CH, then according to Griffin, my CH is fine. Definitely makes me glad I'm waiting on my test kit. But the thing that gets me every time with Griffin is that they are saying my CYA is 90. They ALWAYS say my CYA is high, even if it's not. How is that? Another question: What kind of way do you test CYA with the TF100? I'm hoping it's better than the Jacks Magic because it's almost always hard to read, or at least hard to feel certain I'm reading it right.
    13,500 gallons
    Sand filter
    IG
    Plaster
    TF-100

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    Re: Calcium Hardness question

    Quote Originally Posted by DanaSC
    Another question: What kind of way do you test CYA with the TF100? I'm hoping it's better than the Jacks Magic because it's almost always hard to read, or at least hard to feel certain I'm reading it right.
    In the TF-100, you mix the reagent and pool water in a squeeze bottle, then add the mixture to a viewing tube (while looking down the tube, until the black dot disappears). In my experience, this CYA test has been easy to preform/interpret..and also been very accurate.

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