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Re: Aquatic Plants Digest V4 #52

> Free chlorine gas is not present in chlorinated water.   When chlorine gas
> is added to water, it reacts to form hypochlorite and hydrochloric acid:
> CL2 + H2O --->HOCl + H + Cl
> the hypochlorite can further ionize to form:

> HOCl + NH3 <--> NH2Cl (monochloramine) + H2O
> HOCl + NH3 <--> NHCL2 (dichloramine) + H2O
> HOCl + NH3 <--> NCl3 (nitrogen dichloride) +H2O
> These reactions are dependent upon pH, temperature, contact time, and the
> initial ratio of chlorine to ammonia, but in most cases the predominant
> forms are monochloramine and dichloramine.  The chlorine present in these
> compounds is called the "combined available chlorine".  The addition of
> thiosulphate will neutralize the chlorine but will also liberate the

Thanks Mark for this informative post.  I was using a thiosulfate
neutralizing reaction for bromine that I use in my lab, and although it
probably works with chlorine too, it obviously does not apply here.
I'll just remove my left foot from my mouth.

And no I was not suggesting using thiosulfate for chloramine