I had an interesting conversation with my LFS guy about these water conditioners and he said from a chemistry standpoint you're really better off letting some water stand and off gas itself. The point he was trying to make is that you can't REMOVE one chemical by adding another. I understood what he was trying to say, but not being a chemist wasn't sure what the point was in regards to the health of your fish and tank chemistry. If anyone knows I'd love to hear your thoughts on this.
Andy
So, because I have a love for all things chemistry, andyjh's post sent me to my HS chemistry books and to the Intarweb for the answer. Why is chlorinated city water poisonous to fish, yet the ocean is literally salted to the brim with sodium chloride?
According to
this PDF, the addition of gaseous Cl2 to municipal city water results in a dissociation of both the Cl2 and H20 molecules, forming hypochlorous acid in solution (HOCl). Considering that bleach is a sodium hypochlorite solution, this acid must be the poison factor in city water. Fish, and their owners, need to get rid of this
hypochlorite (Cl0- ion).
Adding oxygens to the ion makes the ion more reactive and poisonous, not to mention explosive when added to the right
alkali metal. So that's not the ticket...The hypochlorite must be reduced (oxygen removed) to form the
friendly CL- ion. Reducing agents such as sodium thiosulfate and sodium hydroxymethanesulphonate (AmQuel's active agent) convert the hypochlorites into nontoxic chlorides by soaking up an oxygen ion.
This is the same safe ion which forms when we add a pinch of common sodium chloride salt (
NaCl). The dangerous hypochlorites are gone! So, you can tell your LFS guy that you can in fact remove one chemical compound from a solution by converting it to another compound. Of course, you already knew this, since ammonia is removed by conversion to nitrate in the nitrogen cycle. Chemistry is cool!!