Subject: Re: NANFA-L-- Chlorine
From: James Smith (jbosmith-in-gmail.com)
Date: Mon Nov 29 2004 - 12:13:45 CST
That's a great explanation.. far more than I ever knew...
Anyway, I just wanted to ask that you should call your water company
and see if they use chloramines. If they do or they plan to in the
future, get a dechlorinator that breaks the ammonia/chlorine bond as
well. Most do now adays, but it's still something to check. Chloramine
doesn't evaporate out like chlorine, even with boiling. I guess that's
why they use it :)
On Mon, 29 Nov 2004 10:56:02 -0700 (MST), Joshua L Wiegert <jlw-in-dune.net> wrote:
> Gah, my telnet server is being cranky and giving me trouble sending out
> e-mail... oh well. Most commercial dechlorinators are sodium thiosulfate.
> In case you care, it is Na2S2O3. In water, Chlorine Gas reacts with water
> to form HOCl, hypochloric acid, and HCl, hydrochloric acid. The
> hypochloric acid is bleach and what does the killing -- its a heavy
> reducing agent (meaning it wants to lose that O atom) an, as such, it
> tends to gain electrons, removing them from other organisms and .. well,
> killing them.
> Itis essentially the same mechanism as how peroxide works on a cut or such
> (though I believe peroxide is an oxidiser, so its the opposite, but...
> still the same... honest!) In water, the tiosulfate ionizes to become
> 2Na+ and S2O3--. By picking up the HO from the hypochloric acid, the S2O3
> becomes neutrally charged, and the Cl is liberated. Since the S2O3 has
> two negative charges on it, it takes two HOCl's to neutralise it --
> resulting in 2 Cls, which quickly bond to become Cl2, the original gas.
> The remaining molecules in the tank are 2HO+ and S2O3, which I believe
> restructure as 2HO+ + S2O3 + H2O = 2H2SO4 -- sulphuric acid. This is part
> of the reason why tanks tend to acidify over time -- though organic
> reactions do much more. In fact, if you ever test the pH of your tap
> water, add dechlorinator and test it again, you'll find a pH drop --
> though it would take a pin point meter to do it. From that change in acid
> concentration in the water, you could theoretically figure out how much
> chlorine is in your water to begin with -- probably easier to call the
> water company and ask! :)
> Now, I have a funny feeling I haven't actually answered any of your
> questions..... The dose of dechlorinator that you add to your tank is
> much, much higher than it needs to be. This is a CYA technique used by
> the companiesmanufacturing their products..... If only 50% of your
> chlorine was neutralised after use, and your fish died... they could be in
> trouble. :) I've often gone on the cheap and used half or even quarter
> doses of sodium thio.
> Ideally, it doesn't matter where or how the thio is added to the water or
> how dilute it is. The reaction is going ot take place. If you don't have
> a lot of turbulance, it'll take time. Ideally, the water is well mixed
> and the thio mixes through it -- this is another reason why you should
> dose the bucket before you pour it into the tank oras you add the water.
> However, in the end, it doesn't really matter too much.
> Also, I must point out:
> HOCl + HCl <--> H2O (Water) + Cl2 (Gas)
> Essentially, when you bubble chlorine gas through water, which is what the
> water company is doing,, you get those two products as explained above.
> But this is a reversable reaction -- given time, the two products will
> recombine to form water and Cl2 Gas, which bubbles out of the tank and
> leaves. This is why you can leave a bucket of water overnight to remove
> the chlorine. The caveat, though, is that without sufficient turbulence,
> the rate of the reaction is slowed down -- that CL2 has to reach the
> surfac e to leave, or it'll just react with more water and go back.
> Boiling not only increases the turbulence, but increases the rate of the
> reaction. Boiling water also has the advantage of causing water to lose
> its temporary hardness..... It can soften it.
> Joshua L. Wiegert
> AIM UID: JoshuaWiegert ICQ UIN: 276060292
> Feel free to contact me by any of the above means for any reason.
> "Nature" is made possible by the Corporation for Public Broadcasting
> Doubt is not a pleasant state of mind, but certainy is absurd.
> -- Voltaire (1767)
> Wise men talk because they have something to say; fools, because they
> have to say something.
> -- Plato
> ... Had this been an actual emergency, we would have fled in terror, and
> you would not have been informed.
> On Mon, 29 Nov 2004, Hoover, Jan J ERDC-EL-MS wrote:
> > Date: Mon, 29 Nov 2004 11:17:49 -0600
> > From: "Hoover, Jan J ERDC-EL-MS" <Jan.J.Hoover-in-erdc.usace.army.mil>
> > Reply-To: nanfa-l-in-nanfa.org
> > To: "'nanfa-l-in-nanfa.org'" <nanfa-l-in-nanfa.org>
> > Subject: NANFA-L-- Chlorine
> > Last week, after topping off three large (> 100 gal) tanks with tap water,
> > the fish in the first of the three tanks turned belly-up. Fish were saved
> > by immediately transferring them to other tanks. While doing water changes,
> > we noticed that water coming out of the tap had a stronger-than-usual odor
> > of chlorine. The total volume of water added to the tanks was small (< 15
> > gal), but we wondered if chlorine could have been the culprit. The incident
> > reminded me that I never have learned how dechlorination works. I wondered:
> > 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 ?
> > Please excuse what may be naive questions from a chemistry- and
> > physics-impaired individual.
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/ reflect the beliefs or goals of NANFA. For more information about NANFA,
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: Fri Dec 31 2004 - 12:42:55 CST