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Re: Aquatic Plants Digest V3 #1025

On May 12, Cheryl Hoffman wrote:
> I finally harassed my Water Company into giving me a report. Would anyone 
> care to comment?

In a word.... Eeewwwwww.

> I'm interested to know what everyone thinks. I'm especially 
> hoping Roger Miller will chime in about sodium. And what would create 
> bicarbonate levels like that? How would you "fix" this water for a South 
> American or Southeast Asian tank?

The sodium level is very high.  Coupled with the low calcium and
magnesium, I imagine that you're plants are struggling.
> Aluminum					< 0.04 mg/l
> Arsenic						< 0.0020
> Barium						   0.004
> Cadmium					< 0.0012
> Chromium					   0.02
> Copper						< 0.006
> Iron							< 0.012
> Lead						< 0.001
> Manganese					< 0.008
> Mercury					< 0.00027
> Nickel						< 0.02
> Selenium					< 0.002
> Silver						< 0.01
> Sodium						   238.00
> Antimony					< 0.002
> Beryllium					< 0.001
> Thallium					< 0.001

Gee.  Thallium.

> Zinc						< 0.02
> Calcium					   1
> Chloride					   21
> Fluoride					   1
> Magnesium					< 1
> Total Nitrate				< 0.01
> Sodium						   268  (again? Why 
> different?)

Sometimes water reports are divided into several sections.  It appears
that in the original report, metals (inclusive of sodium, which might be
grouped with metals) may have been in one section while major ions
(also including sodium) are reported in another section.  There might be
other sections on pesticides, volatile organics, bacteria, etc. etc.

Probably your water utility summarized a larger report to give you this
result.  They may have overlooked the overlap in reporting sodium, or they
may have intentionally included it twice because the original report
appeared to be in error.

I did a quick calculation to figure out which might be more accurate, and
it appears that the higher of these two (268 mg/l) is more probably
correct.  Whichever is right, your water contains a lot of sodium.

> Sulfate 97 
> Total Hardness as CaCO3	< 2
> pH							   8.8
> Dil.Conduct (umhos/cm)		   1148

The State of Texas' water quality lab is the only lab I've ever seen
report "Dil. Conduct"ance.  I imagine they were the original source for
this report.

> Tot. Alka. as CaCO3		   454
> Bicarbonate					   503
> Carbonate					   25

The alkalinity values are consistent with each other and with the high pH.
Carbonate is present only at high pH.

Given that pH, sodium and alkalinity are all high, I wonder if this water
might have been treated with sodium carbonate to increase pH.  This could
have the side effect of decreasing the hardness, which is surprisingly

This would be an unusual natural water composition.

> Dissolved Solids			   660

I think this exceeds the state's drinking water standard, which is 500
mg/l if I remember right.  But don't feel lonely.  Lots of towns in Texas
have a hard time reaching that standard, which is an aesthetic standard
anyway, and not a health standard.

The dissolved solids from the sum of constituents (using the higher
sodium value) is 635 - a little lower than the 660 reported.  The
difference could be accounted for with silica, which is often found in the
range of 10-20 mg/l, or potassium, which is unfortunately omitted from
this table.

> P. Alkalinity as CaCO3 21 (what does this mean?) 

Phenolthalein (sp?) alkalinity.  It measures alkalinity created mostly by
carbonate and is zero for water with a moderate or low pH.  Your pH is
high.  I don't remember what the exact endpoint on the titration is.

> Residual Chlorine Not Detected

That's not good if this is treated water at the tap.

Anyway, your plants probably need more magnesium and calcium than this
water gives them.

You might be able to provide that by adding dolomite to the substrate and
possibly adding something else to help keep it available to the plants.  
I might add peat for that.

As a second choice, you might experiment with adding calcium or magnesium
to the water, but your sodium concentration is so high that you might have
to add a *lot* of magnesium and calcium to get them balanced with the
sodium - enough that the resulting mix would be brackish.

The third alternative would be to reconstitute water from RO water,
rain water, or solar-distilled water.  That way you can get any water
composition your heart desires.

Roger Miller

P.S.  I don't mind being asked to chime in, but I think that when you
mention an individual who you would like to respond it might discourage
others from answering the same question.