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Julie De Merchant posted about neutralizing Chlorine with thiosulphate:
> Tap water typically will not have more than 1ppm chlorine at the tap, some
> treatment plants aim for 1ppm Cl at the exit of the treatment plant so
> that by the time it reaches your tap, there should still be a residual.
> In North America, the 1ppm is often true, but I believe Europe uses a
> lower level of chlorine at the exit of treatment.
I'm no chemist, but you have to be careful about Chlorine (Chloramine)
levels - they vary not only from city to city, but from month to month in
the same city as well. The latest Toronto water analysis (Julie, I gave you
a copy last summer) listed a Chlorine residual varying from a high of 2.30
ppm down to a low of 0.93 ppm, depending upon the month the test was
conducted. Now, this is at the plant, and not at the tap but as the risk of
thiosulphate overdose is minimal (within reasonable limits) it might be best
to assume that tapwater contains more rather than less, just to be sure that
it is neutralized.
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.
Now, since I'm NOT a chemist, and I can't remember if this has been answered
before - is there anything OTHER than Amquel or Prime which will break the
chloramine bond but WON'T interfere with test kits? I've read where Nessler
method kits for Ammonia won't read accurately if the water has been treated
with either Amquel or Prime, and the same problem exists with Winkler method
Dissolved Oxygen kits.