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Re: Thiosulphate


Date: Sun, 23 Jan 2000 16:49:31 -0600
From: "James Purchase" <jpurch at interlog_com>
Subject: RE: Thiosulphate

> Julie De Merchant posted about neutralizing Chlorine with thiosulphate:
> Additionally, thiosulphate (as far as I know) won't do squat with chloramine
> (chlorine + ammonia), so a hobbyist should always contact their local
> supplier and find out how their own water is treated and treat accordingly.

Not true! First, the results of using it on chloramine can easily kill your

The hypo (sodium thiosulphate) works exactly like it does on chlorine alone,
but that can result in a burst of ammonia/ammonium that can be even more
lethal than the chlorine would have been. In So. CA they have as much a 3
ppm of chloramine in the water at times. In Spotte, it is reported that less
than 0.1 ppm of ammonia can cause permanent gill damage and stunting of baby
fish. At low pH it is not a problem, as the harmless ammonium form is
dominant. At pH well above 7 (now mandated by EPA in most areas to stop
lead/copper pipe erosion), it quickly becomes lethal as it is converted to
ammonia. The ammonia is ten time more lethal at pH of 8 than at 7, and about
60 times more at pH equals 8.8. This is the source, BTW, of much of the
mythology about pH shock, with osmicity (tds shock) being the rest.

Does this explain why reef and Tanganican tanks are so tricky to maintain?

Second, in many agricultural areas, the ammonium is already in the
ground-water supply. The water service does not need to add it. They rarely,
if ever, test for that. There is little reason, anywhere, to not use Amquel,
Prime o/e, IMHO. Observations of local members of the SFBAAPS indicate that
the ammonia/ammonium bound by the Amquel is still readily available to the
plants. Since that report, I have used Amquel in all my aquarium water and
see no harm to the plants, thereby. By using an excess over what is needed
to handle our weak chloramine (<1 ppm) I give the fish a break by
sequestering even more of *their* ammonia with every water change.


Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com

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