Re: [Killietalk] What's in my water

[Wright Huntley <whuntley at inkmkr_com>]

I agree with Barry and would add a comment. Pure sodium chloride in RO 
water (o/e) is essentially toxic. I believe this is because cell 
transport requires the interaction of two or more electrolytes to be 
effective (or some such story). They need to be in some very rough 
balance, I think.

In particular, I think I once read that potassium and sodium ions are 
very interactive in cellular transfer processes. You also really need at 
least a little Ca++ and Mg++ plus a host of trace elements to make water 
really healthy for plants and fish. I refuse to count on fish food to 
give me those.

I nearly killed all my plants and made my fish very sick, when I moved 
to Modesto and treated the pure Sierra snow runoff (<50ppm) with salt to 
raise tds a bit. They all bounced back rather quickly when I added 
"Equilibrium" from Seachem.

Wright

Edd Kray wrote:
> Putting together all this chemistry talk (good) with my question on RO
> water:
> 
> I don't like the idea of adding any of my tap water back in because it's the
> Ca/Mg I want to make "go away" and it will put it back in along with the
> very strong buffering that keeps my water above 8.
> 
> I don't like using some commercial product when no-one can tell me what's in
> it and what I'm adding back.
> 
> Why not just plain Salt (NaCl), It'll give me a know chemistry, add back
> some ionic strength and conductivity, counteract osmotic stress and it's
> cheap (lots cheaper that a product like Equillibrium)
> 
> See any problems with that?
> 
> -----Original Message-----
> From: killietalk-bounces+edd=catfishnthecrawlers_com at aka.org
> [mailto:killietalk-bounces+edd=catfishnthecrawlers_com at aka.org] On Behalf Of
> Koran, David HQ02
> Sent: Friday, February 03, 2006 11:16 AM
> To: killietalk at aka_org
> Subject: [Killietalk] What's in my water
> 
> As Charlie has stated you are measuring apples and trying to state the
> result
> as oranges.  When you measure conductivity this is a sum of a concentration
> of charges so to speak.  You sum the molal conductivities of the components
> of your solution.  Molality is a concentration term based on weight per
> weight, i.e., the number or fraction of atomic/molecular weights of an ion
> in
> a kilogram of water.  Molal conductivity is also a function of the charge of
> the ion.  To simplify matters you can approximate an average value for ionic
> conductivities and then use this artificial factor to relate the electrical
> measurement to weight of dissolved solids in your solution.
> 
> To find the weight of dissolved solids you must eliminate the solution
> (water) or "dry the sample".
> 
> Osmotic pressure is also the sum of osmotic pressures of the solution
> components.  In this case the component osmotic pressure is a linear
> function
> of the molality of the component.  The net directional flow of water across
> a
> permeable membrane (i.e., cell wall) is determined the net difference of
> component osmotic pressures.
> 
> Hardness is a subjective measurement of the ability of soap in a water
> sample
> to form a lather or bubbles.  You can measure the concentration of
> multivalent cations in a solution by a "complexometric titration" and
> multiple by a factor to relate to hardness.  Hardness test kits add a simple
> alkaline buffer to your test solution and an indicator complexing agent
> which
> quickly binds to your multivalent ions in the test solution (that ions with
> a
> charge of +2 or more, namely calcium and magnesium but this will also hold
> true for iron and other metal cations which are probably in not much of a
> concentration).  When you add your 3rd solution you are actually titrating
> your metal ions with a more effective complexing agent than the indicator.
> This titrating agent is solution of a known concentration of EDTA (you see
> this in a lot of products! And is the chemical abbreviation for
> ethylenediaminetetraacetic acid which has 6 binding sites and effectively
> blankets each metal ion).  You add titrating solution until the EDTA
> scavenges every multivalent ion in solution and then out-competes the
> indicator for the metal ions it previously tied up.  At your end point or
> read out point you see a color change and that is when you have an excess of
> freed indicator (acid) over the metal ion-indicator complex ion.  You chose
> your indicator such that the color change (in solution) between the two
> forms
> is dramatic.  By rigging the concentration of solution you drop into your
> test solution to some concentration which is a multiple of what maybe
> doubling the volume (by addition of test solution) you can count drops and
> get an approximation of what the initial concentration of your multivalent
> ions were.  Remember, here again you have ions of different atomic weight
> but
> for simplicity sake you assume all multivalent ions you titrate/complex are
> calcium.  For the test kits you buy, calmagite is usually the indicator and
> in the free ionic acid form it is produces a blue solution (actually the
> conjugate base is a blue ion or absorbs light in all but the blue region of
> the spectrum) whereas when it is complexed with calcium ion it imparts a red
> color to water.
> 
> Notice that in all of this discussion nothing was said about measuring
> monovalent ions or the ions of your akali metals; sodium, potassium and
> lithium.  It should also be noted that in measuring conductivity, calcium
> and
> magnesium ion will produce twice the conductivity of the akali metel ions.
> As hardness goes, it relates to the amount of multivalent ions present.  You
> form soaps and lubricants by breaking down polyglycols with a strong base
> (lye or sodium hydroxide) and form a salt of a fatty acid.  These soaps are
> much more soluble than the parent fatty acid but when paired with a
> multivalent ion like calcium or magnesium they readily form a precipitate
> and
> drop from solution.  You, therefore, don't simulate hard water by simply
> adding salt, i.e., sodium chloride.
> 
> I know, ack, chemistry lessons on a Friday afternoon...you can now look for
> your beer.
> 
> Dave K 
> 
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> 

-- 
Wright Huntley - Rt. 001 Box K36, Bishop CA 93514 - whuntley at verizon_net 
  760 937-2276 (mobile) 760 874-2000 (CA) or 941 866-0500 (FL).

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Unless you’re crazy” -- Chad Carter.

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