I realized I have the perfect venue to find out in you marvelous people. I've been using them for decades but don't know how exactly they work.

The main active ingrediant in most of them is sodium thiosulfate.

(I'm not sure what a "thio" is, but if it's latin for "pile on the extra stink" then they named it correctly. The stuff has an abominable stench.)

Thank you.

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Gimme a minute to read through Jay's latest observations...

looking at wiki, it looks like you prolly get a double reaction. The thiosulfate converts the chlorine to a chlorine ion then the ion reacts with the sodium.

I studied chemistry in my first year at university, and I'm not sure what you mean by a "double reaction". I think you mean a redox reaction. But basically you are right with the first bit, in this context thiosulphate is a reducing agent which reduces the chlorine to chloride (while it is oxidised to sulphate). Chloride ions do not "react" with sodium ions.

Thio- comes from the Greek for sulphur. Thiosulphate is S₂O₃^2-. The thio- prefix indicates that one oxygen atom in a sulphate ion SO₄^2- has been replaced with a sulphur atom. Similarly, thiols are like alcohols, but with the oxygen atom in an alcohol replaced by a sulphur atom. The older name for a thiol is a mercaptan.

Ivan Correct. Big Don raises tropical fish, and a touch of thiosulfate eliminates free chlorine in chlorinated tap water....replacing it with a touch of table salt...far more innocuous. For tap water drinkers....boiling your tap water will drive it off...then cool....shake to aerate...and forget money wasted on bottled water. You need a little salt in your diet for healthy gums anyway.
It's also the primary ingredient in most photographic "fixer" baths as it complexes out silver bromide. You can reclaim the silver with a little steel wool....and a little chemistry. I used to save ~ $250,000 a year in one job. pete

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A third rate theory forbids
A second rate theory explains after the fact
A first rate theory predicts...A. Lomonosov

You might already do it but if you buy pond dechlorinator instead of aquarium dechlorinator 10ml will be enough to treat 40gallons.

Better than that KLIK is a product called Prime. I use one measured drop to four gallons. (Most five gallon buckets are five gallons at the rim. That's too full to do anything useful with without spilling, so you back it down a gallon to give you enough lip.) It's concentrated liquid sodium thiosulphate. Don't spill it. It's a bit whiffy.

So if you have alcohols with oxygen and thiols with sulfer, what do you call compounds that are chlorine and flourine based? And isn't bromine in that group as well?

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Gimme a minute to read through Jay's latest observations...

I am making the completely unwarranted assumption that after the chlorine atoms are reduced to chlorine ions, they will then 'react' with the sodium ions left over from dissolving the sodium thiosulfate, leaving salt. I dunno the proper terminology for how that occurs when in solution. I do know that my terminology is sloppy tho, since everything will stay as ions as long as there is enough water to keep everything dissolved

Its a little more complicated than that. Oxygen can form oxides, hydroxides, ethers, esters, etc. Simillarly, sulfur can form sulfides, sulfates, sulfites, thiols... It all depends if we are talking organic or inorganic compounds and what else is involved. Chemical nomenclature can be complex.

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At night the stars put on a show for free (Carole King)

One Earth, One Sky - IYA 2009

I just leave my Aquarium change water overnight and bubble it with an air pump.

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'The eye can only see what the mind is prepared to accept'

Yes that can work, but my water system switched to chloramines instead of chlorine. That trick doesn't work anymore for me. (Chlorine/ammonia combo)


NEW SUBJECT

Okay, I need some BS filtration here people. One website was trying to tell me ammonia is a carcinogen. I find this difficult to believe, other than in the context of a something irritating mucus membranes and causing those cancers that arise from healing of mucus membranes that have been damaged. Like those poor kids who drink bleach as a small child and then develope esophogeal cancers as adolescents. Or people who drink straight hard liquors above a certain proof, that escapes me at the moment.

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Gimme a minute to read through Jay's latest observations...

Almost anything can be shown to be a carcinogen given the proper conditions.
Remember cyclamates? They were banned before anybody bothered to tell us that they cause cancer in lab rats when the dosage was the equivalent of 800 cans of diet cola per day!

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Any day you wake up on "the right side of the dirt" is a good day.

T. Anderson

I still wanna see 'clinical proof' that water is a carcinogen

Quite so. That's why there is no reaction between them. And even if the water is evaporated and sodium chloride crystals are precipitated, that wouldn't be called a reaction either, because it remains ionic in the solid state too.

F, Cl, Br and I are the halogens, traditional Group VII (modern 17). The names of their generic classes of compound tend to have hal- in their names, like halides. Halogen chemistry is dominated by the fact that they are all very electronegative, so they tend to be rather similar. O, S, Se are traditionally Group VI (modern 17, the generic name chalcogen is not in common use). Group VI chemistry is more complicated than Group VII, and the differences are much greater than between the halogens.
http://en.wikipedia.org/wiki/Periodic_table is a good starting point for looking at the basic chemistry of the elements and their groups.

I did not know that. Thanks