[APD] Hardness, alkalinity, and RO

["Douglas Guynn" <d_guynn at sbcglobal.net>]

Perhaps I'm missing something here, but this is my take on this discussion.
Hope my ramblings aren't too confusing. Here we go...

First, the tap water here in West Texas is liquid rock as follows;
	GH, around 34 (not 3.4)
	dissolved solids, around 1400 mg/l
	conductivity, around 3000 micro-mhos/cm
	chlorides, over 450 mg/l
	sodium, over 250mg/l
	sulfate, nearly 400 mg/l (makes the water taste like liquid something else)
	Chloramine used as disinfectant
This sample was taken in the summer when the surface water we drink is
supplemented with ground water from some VERY deep wells in the surrounding
area. The ground water analysis is substantially lower than the above
"mixed" sample, so you can imagine what the analysis looks like in the
winter, when we rely on surface water only, especially after a long, hot,
dry summer when mother nature has taken her share of the H20 part of the
liquid due to evaporation.

Second, KH is not actually a measure of hardness, but a measure of
alkalinity (buffering capacity, or resistance to pH shift). GH is a measure
of true hardness. Hardness (GH) is a measure of the Calcium (Ca) and
Magnesium (Mg) and a few other minor impact cations content of water,
expressed as Calcium Carbonate equilivants. Alkalinity (KH) is the carbonate
and a few other minor impact anions content of the water, also expressed as
Calcium Carbonate equilivants. Same units (which may have resulted in both
being deemed "hardness" by the trade), different stuff. The same units are
used because the lions share of Ca and Mg is in the form of carbonates, at
least in natural water systems. Interestingly enough they are also found,
more often than not, in nearly the 2:1 ratio mentioned in this thread (Ca is
in the 120's and Mg in the 60's here) .

Third, If you want to decrease the sodium content of water, RO does that
very well. Once that is accomplished, reconstitute it to a useable condition
by adding a little of the raw water from your tap to the product from the RO
unit until the desired KH, GH, TDS, conductivity, smell, or whatever target
you choose to use is reached.  I've been doing that for nearly 5 years, and
have never had any trouble. I don't even use a de-chlor of ANY kind when I
do a 20% water change. I change 20 gallons of water (made up of 15 gals RO
water and 5 gals of tap water) and never see any effect except some pearling
from my plants and a feeding frenzy from my fish.

Douglas Guynn
        432.368.5411
        d.guynn at sbcglobal.net

"Republics are created by the virtue, public spirit, and intelligence of the
citizens. They fall, when the wise are banished from the public councils,
because they dare to be honest, and the profligate are rewarded, because
they flatter the people, in order to betray them." - Joseph Story


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