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Re: Softened Water - Estimated Sodium in softened water - correction

Thanks Roger Miller for finding my stupid mistake!!!!!

>Date: Wed, 24 Sep 1997 12:16:31 -0500 (EST)
>From: "Roger S. Miller" <rgrmill at rt66_com>
>Subject: Re: softened water
>
>>
> Date: Wed, 24 Sep 1997 10:54:31 -0400
>> From: rjw at aluxs_micro.lucent.com (Ronald Wozniak)
>> Subject: Re: Softened Water
>>
>
>[lots of review and background snipped]
>
>>
>> 1 degree GH = 17.9 ppm Ca = 2 x 23/40 x 17.9  = 20.6 ppm Na
>>
>
A (German) degree of hardness is 17.9 ppm hardness as _CaCO3_, which
>isn't the same thing as 17.9 ppm of Ca.  There are 40 parts of Ca for
>each 100 parts of CaCO3, so:
>
>1 degree GH = 17.9 ppm hardness as CaCO3
>17.9 (ppm CaCO3) X 40(Ca)/100(CaCO3) = 7.16 ppm Ca
>
>Now going back through the rest of your calc:
>
>7.16 ppm Ca => 2 X 23/40 * 7.16 = 8.23 ppm Na.
>
>or softening 1 degree GH produces 8.2 ppm of sodium - the same number I
>cited earlier.
>
>
>Roger Miller

Please disreguard my last post.  Here's the correction:

Estimating the Amount of Sodium in Softened Water
------------------------------------------------

Watersoftners use Zeolite to remove "hard water" minerals from your household
water.  The basic formula for conversion is given (ASCII art) by:

      2NaSiAlSO4      +      Ca++      ->      Ca(AlSi04)2      +      2Na+

     (Sodium Aluminum       (Calcium            (Calcium Aluminum       ( Sodium
       Silicate)              ion)               Silicate)                ion)

      (Magnesium ion (Mg++) can be substituted for the calcium ion.)

This equation says (do to charge conservation) that two sodium ions are needed to
replace one calcium ion.

Watersoftners do a good job of removing most of the calcium and magnesium. When
I measure the hardness of softened water, it is below 0.5 degrees GH. (Limited by
my test kit.)

By knowing the atomic weights of calcium and sodium (Ca => 40 and Na => 23), and

(Thanks to Roger Miller)
A (German) degree of hardness is 17.9 ppm hardness as _CaCO3_, which
isn't the same thing as 17.9 ppm of Ca.  There are 40 parts of Ca for
each 100 parts of CaCO3.

1 degree GH = 17.9 ppm as CaCO3 => >17.9 (ppm CaCO3) X 40(Ca)/100(CaCO3) = 7.16 ppm Ca

and.....
using Neil Frank's article "Determining the Concentrations of Chemicals Added to
the Aquarium" TAG Vol.10 No. 2, I can determine how much sodium would be in
softening water that was 1 degree GH hard.

So, using the assumption that each calcium atom is replaced by two sodium atoms:

1 degree GH = 7.16 ppm Ca => 2 x 23/40 x 7.16  = 8.23 ppm Na

From which we can produce the following little reference table:

Estimated Sodium in softened water     ( 1ppm = 1mg/liter)
----------------------------------
   |Before GH  |Converted Na |
   | (degrees) | (mg/liter)  |
   |-----------| ------------|
   |     1     |     8.2     |
   |     2     |     16      |
   |     5     |     41      |
   |     10    |     82      |
   |     15    |    123      |
   |     20    |    165      |
   |     25    |    206      |
   |     30    |    247      |
   ---------------------------

Another thing to remember, a watersoftner waste salt when it recharges the Zeolite.
Thus, one may expect to get even higher levels of sodium just after the recharge.

Let's get a feel for what these numbers mean.

Water hardness follows these guidelines:

      0 -  4 dH,    0 -   70 ppm : very soft
      4 -  8 dH,   70 -  140 ppm : soft
      8 - 12 dH,  140 -  210 ppm : medium hard
     12 - 18 dH,  210 -  320 ppm : fairly hard
     18 - 30 dH,  320 -  530 ppm : hard
      above                      : very hard

The water in the Allentown area is around 12 degrees, which means
I'd estimate my water sodium concentration to be about 100 mg/liter.

A lot of us use baking soda (NaHCO3 a.k.a. sodium bicarbonate) to raise the KH
in RO water to about 4 degrees KH.  How much sodium is that?

In Neil Frank's article 30 mg/l of sodium bicarbonate gives a KH of one degree.
(1.1 teaspoons (5.68g) in 50 U.S. gallons)

So, 4 degrees KH => 4 * 30mg/l * 23(Na)/84(NaHCO3) = 4 * 8.21 = 33 mg/l Na

For humans, consuming less than 2400mg per day is recommended. (U.S. Dept.
of Agriculture?)

Maybe someone on the list can comment about which fish and plants are sensitive 
to sodium and at what levels.

---------------

I apologize for the previous error in APD V2 #974.

Ron Wozniak  Allentown PA, USA
rjwozniak at lucent_com