[Fish4Fun]

Hi All!

There are two typical methods of neutralizing Ammonia in aquatic systems:

1) "Biological Filters" which promote the growth of microbes that "eat" ammonia and metabolize it to non-toxic molecules
2) Addition of Chemicals to "Neutralize" Ammonia ... typically converting it to some type of Ammonium molecule.

A commonly used chemical for neutralizing Ammonia in consumer to industrial scale operations is Sodium Thiosulfate.  Other notable chemicals include Sodium Methanesulfonate and Sodium Hydroxymethane Sulfonate (both "proprietary" chemicals patented by 'Aquascience Research Group' for Ammonia and Chlorine Neutralization in aquatic systems). 

I am researching a water treatment for saltwater fish tanks and need to make an informed decision about the efficacy of various Ammonia Neutralizers.  I passed both high school and college chemistry back in the early 1980's, but I am certainly NOT a chemist.  So, first thing first, I want to make sure I have a grasp on the stoichiometric progression of Sodium Thiosulfate and Ammonia....

Na2S2O3 + 2(NH3) --> (NH4)2S2O3 + (Na+)

One would assume the Sodium ion would bind with a free Chlorine ion if available thus fulfilling its side task of "Chlorine Neutralizer".

Now, assuming I have Sodium Thiosulfate -> Ammonium Thiosulfate figured correctly, I am at a loss with Sodium Methanesulfonate (CH3SO3Na) and Sodium Hydroxymethane Sulfonate CH4NaO4S+ .  While "Methane" is obviously bound to the sulfate and (perhaps) more loosely to the Sodium atom I can't figure out how either of these in the presence of Ammonia "progress" to some form of Ammonium Sulfate without the carbon atom 1) Remaining Bound to the 4 Hydrogen Atoms and being released as Methane  OR binding to oxygen to form 2) CO or 3) CO2 by taking dissolved oxygen from the solution.  I am sure there is a simple answer, I just haven't done much chemistry in the last 3 decades.

My primary interest is determining if there is any chemically sound reason to select a proprietary Ammonia Neutralizer in favor of a considerably cheaper generic commodity chemical.  If either of the proprietary chemicals have a > 5:1 efficacy over the Sodium Thiosulfate then it would be worth considering them; if not, then the only advantage might be marketing. 

Thanks in Advance!

Fish

[Borek]

Na2S2O3 + 2(NH3) --> (NH4)2S2O3 + (Na+)

That's definitely wrong.

Thiosulfate is a good reducing agent used to remove things like chlorine, I on't see how it can remove ammonia. What you wrote requires protonation of ammonia (so some source of H⁺) - but as ammonium ion it will be still present in water, so it is hardly "removed".

At typical pH of sea water most ammonia is already protonated, trick is, buffering properties of the sea water are not enough to keep the pH constant if ammonia is added.

[Arkcon]

Much of your chemistry is flat out wrong.  Sorry, I had to say it, and had to say it in that way, or people will write ling diatrabes like yours that will take this thread nowhere. 

Here, when I Google, "Sodium Thiosulfate remove ammonia", the first result says that it doesn't do that.  http://www.angelsplus.com/ArticleChloramine.htm  You don't need a recent high school chemistry class to Goggle correctly.  So balancing your equation, or determining if it will go forward, or saying what really happens isn't at issue here.

We do have experts on this forum who may be able to satisfy your curiosity as to why aliphatic amines "detoxify" ammonia in aquariums.  They may not be reacting with the free ammonia, they may simply be changing the environment so the ammonia is less of a problem, they may even function as nutrition for aquarium bacteria, causing hem to bloom and consume the ammonia faster.

[Fish4Fun]

@Borek and Arkon ...

Thanks for the responses! 

I obviously do not have the knowledge about chemistry that you possess.  As to **My chemistry being flat out wrong**: I certainly am not going to argue that point, nor do I care about being "right" on any other particular point.  What I am interested in is making informed decisions about chemical additions to decrease mortality in salt water tanks with high biomass loads.

@Arkcon ... the link you reference states the following:

Ammonia is not toxic at a pH below 7.0. This happens because in acid conditions, free hydrogen ions convert it to ammonium NH4. As pH rises above 7.0, these hydrogen ions are less available, leaving more toxic ammonia (NH3).

While I have read a great deal about various chemicals used for water treatment, I had not grasped the relationship between pH and NH3 // NH4 until reading Borek's post and then the above quoted passage . I had previously assumed that the addition of Sodium Thiosulfate was at least partially responsible for converting NH3 to NH4 and that the proprietary formulations were also somehow linked to the conversion of NH3 to NH4.  Obviously my assumptions were completely false.

@Borek's salient contribution:

What you wrote requires protonation of ammonia (so some source of H+) - but as ammonium ion it will be still present in water, so it is hardly "removed".

(FWIW, I never once used the verb "to remove" in my post, whatever else I may have wrong, I was aware that the goal was to favor NH4 over NH3; NH3 is highly toxic to fish while NH4 is somewhat more benign.  I did not realize that the migration from NH3 to NH4 to NH3 was dynamically linked to pH ... )

Perhaps existing products marketed as "Ammonia Detoxifiers" and "Ammonia Neutralizers" that contain Sodium Thiosulfate, Sodium Methanesulfonate and Sodium Hydroxymethane Sulfonate also use some type of pH buffer // reducer to favor the formation of Ammonium over Ammonia and the above listed chemicals are simply present to remove Chloramines?  I will work under the assumption that this is in fact the case, but would truly appreciate any input or thoughts people might have about fish friendly ways to reduce/buffer the pH to minimize the NH3 in favor of NH4. 

@Arkcon

You don't need a recent high school chemistry class to Goggle correctly.

No I do not.  Is this Germain?   


Thanks!

Fish