Re: NANFA-L-- Chlorine

Subject: Re: NANFA-L-- Chlorine
From: Irate Mormon (
Date: Mon Nov 29 2004 - 12:29:45 CST

Quoting "Hoover, Jan J ERDC-EL-MS" <>:

> Are commercially-produced dechlorinators "sensitive" only to variation in
> water volume and not concentration of chlorine ? Is the recommended dosage
> (e.g., 1 drop per gallon, or 1 ml per gal) based on a presumed maximum
> concentration of chlorine used in most municipal water systems ?
> Do dechlorinators effectively neutralize chlorine when tap water is diluted
> with aged water? For example, when making a 20 gal water change to a 60 gal
> tank, should you add 20 gal worth of dechlorinator or 60 gal worth ?

Great question - here is how it works in Pelahatchie:

Each well has a chlorinator attached to it (liquid chlorine, probably sodium
hypochlorite). The chlorinators add solution when the well is running and shut
off when the well is not running. The water flow-in-each pumping station is
constant (when it is on), and the amount of chlorine added-in-each station is
therefore constant, BUT differs from station to station because each station
has a different pumping rate. Also, the initial chlorine concentration is
determined by how long the line is attached to that station - the chlorine
degrades (I was told it has a life of 24 hours) over time, so the longer the
water stays in the line, the higher the initial concentration must be in order
to meet the mandated .5 ppb AT THE END OF THE LINE. What this means is,
chlorine concentration increases as you get closer to the pump. What this also
means is that as water usage increases, so does the chlorine concentration
because it hasn't had as much time to degrade. So, during times of high water
usage your chlorine level may be significantly higher than usual.

The Certified Operator I spoke to also keeps fish, and he was emphatic that you
should NEVER, EVER add water directly from the tap. He recommends adding your
dechlorinator and aging the water for 24 hours. Like many of us, I am often
lazy in that respect, and have had some unfortunate experiences as a result.

To answer the last question, you should add the amount of dechlorinator strictly
according to the amount of tap water you are introducing, not the amount of
tap/aged water.

> Please excuse what may be naive questions from a chemistry- and
> physics-impaired individual.

Haha, I rather doubt that, Jan :-)

"In our study of natural objects we are approaching the thoughts of the Creator,
reading his conceptions, interpreting a system that is His and not ours." -
Louis Agassiz
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: Fri Dec 31 2004 - 12:42:55 CST