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Re: Boiling water



On Wed, 17 Mar 1999, Cheryl Hofmann wrote:

[snip]

> My tap water is very strange. It has no general hardness but 18 - 20 dKH and a
> pH of more than 8.0. The books just don't cover this combination.

I'll guess that Oak Point is using lime softening (the water softening
method that George S. described recently) - it lowers the general
hardness, depletes all CO2 from the water and pushes pH to very high
values.  By the time its delived at the tap the pH can be quite a bit
lower and often continues to drop after it's exposed to air.  Dallas uses
lime softening, Fort Worth (by most recent info) does not.

A very effective ion exchange water softener (Hey Culligan Man!) can
produce water with little or no GH and a substantial KH.  My tap water
has low GH and high KH (though not as high as yours) for natural reasons.
There are a few other areas with similarly odd water for natural reasons.

> I tried
> boiling the water once, and the KH actually ROSE several degrees.

If your GH is very low, then boiling it should have no effect on GH.  I'm
not sure why KH might increase.

> I have begun
> to import water from nearby Denton, except for a (I think) boron deficiency it
> is great water.

I don't know how you might distinguish between a boron deficiency and a
calcium deficiency.  Boron is needed in only very small amounts and
whatever comes in the tap water is usually adequate.  Calcium is usually
the biggest part of general hardness.  Usually, a calcium deficiency is
more likely than a boron deficiency, especially if the water is soft.

I don't know for sure that this is a problem, but I've mentioned it here
and I'll mention it again.

I've read that calcium deficiencies can occur in crops grown in soils with
a high sodium content even if the calcium content is what might normally
be considered adequate.  I think I see similar behavior in my aquariums.
My tap water is soft and well buffered - about 2 degrees GH and 7 degrees
of alkalinity - and sodium is relatively high. The calcium content
(general hardness) is low but appears adequate for plant growth.  The
plants seem to disagree; several species of plants grown under bright
lighting often show calcium deficiency symptoms.

I'm not sure what the mechanism is (I have a theory), but it appears to me
that high sodium levels can keep plants from using the available calcium.
If the water you're using has a low GH and a high sodium content there may
be a chance of seeing this sort of induced calcium deficiency.

You should be able to get a water analysis from your water utility, or
from the Denton water utility.  The analysis should let you compare the
sodium and calcium levels.  You can also check on the boron content
(plants only need a few micrograms per liter, or ppb); if the analysis
they provide doesn't include boron you should be able to call the utility
and ask specifically about the boron content.

If you have a water softener you almost certainly will have sodium levels
far in excess of calcium levels.  In fact, any time that the alkalinity
(KH) is much higher than GH you will probably have sodium levels that
exceed the calcium.


Roger Miller