# Water chemistry



## Hallyx (Jun 11, 2011)

We've been batting some ideas and questions around on this thread. 
http://www.tropicalfishkeeping.com/...rium/cycle-i-know-i-should-know-274570/page3/

Some of us thought it would be better to continue on it's own thread. 

Any and all questions, comments on water quality, cycling, treatment, filtering, chemicals.....etc.


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## rickey (Jul 7, 2013)

*pH, Carbon Dioxide (CO2) and Alkalinity*

The pH of water is an index of hydrogen ion (H+) activity of water. The pH scale
(range from 0 to 14) is logarithmic (base 10), an important fact to remember because a dropof 1 pH unit indicates a 10 fold increase in hydrogen ions (H+) present in water. A pH value may fall anywhere on a scale from 0 (strongly acidic) to 14 (strongly basic or alkaline), with a value of 7 representing neutrality (= 10-7 moles/liter of H+ ions).
The pH of most productive natural waters that are unaffected by pollution is normally in therange of 6.5 to 8.5 at sunrise, typically closer to 7 than 8. Diurnal variation is related to photosynthesis:

(1) CO2 + H2O <-------> C6H12O6 + O2

The controlling factor for pH in most aquacultural is the relationship between algal photosynthesis, carbon dioxide (CO2), and the bicarbonate (HC03-+H) buffering system:
(2) CO2 + H2O <-------> H2C03 <--------> HC03- + H+
At night, respiration by bacteria, plants, and animals results in oxygen consumption and carbon dioxide production, the reaction in formula (2) goes from left to right, first producing carbonic acid (H2C03), then bicarbonate HC03- and H+ ions; the increase in H+ causes the pH to drop. During sunlight, respiration continues, but algae use CO2 for photosynthesis, formula (1); the reaction of formula (1) goes from right to left, reducing the abundance of H+ ions, and pH goes up. In productive ponds, especially those with low alkalinity, the daytime pH may reach 10, which can be lethal to young fish. Toxicity of other compounds to fish, especially ammonia and chlorine, are affected by pH


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## Hallyx (Jun 11, 2011)

So that swapping back and forth of the H+ ion between carbonic acid and bicarbonate is where the H+ comes form that ionizes ammonia into ammonium?

Prime adds lots of H+ Is that it? I'm missing something. Why doesn't this pH go down when you add Prime?


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## Quantum (Jul 23, 2011)

ammonia/ammonium ratio is primarily a function of pH, Prime, apparently does not affect or is not affected by pH, so the manner in which Prime neutralizes ammonia must be other than a simple ammonia to ammonium conversion


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## beaslbob (Oct 17, 2012)

Hallyx said:


> So that swapping back and forth of the H+ ion between carbonic acid and bicarbonate is where the H+ comes form that ionizes ammonia into ammonium?
> 
> Prime adds lots of H+ Is that it? I'm missing something. *Why doesn't this pH go down when you add Prime?[*/quote]
> 
> ...


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## rickey (Jul 7, 2013)

Seachem Priime  is a reducing agent technically a complexed hydrosulfite salt (Sodium formaldehydebisulfite CH4O4S ) Sodium Hydrosulfite is a very strong reducing agent. A reducing agent is the opposite of an oxidant as it will reduce and or remove any oxidant such as chlorine, ozone, chlorine dioxide, just to name a few it will also remove oxygen. Other products, such as hydroxymethanesulfonate (HOCH2SO3-; a known ammonia binder can be used to treat chloraminated water because they both break down chloramine and bind up the ammonia.

The reaction of ammonia with hydroxymethanesulfonate is mechanistically complicated, possibly involving decomposition to formaldehyde and reformation to the product (aminomethanesulfonate). The simplified overall reaction is believed to be:

NH3 + HOCH2SO3- -------> H2NCH2SO3- + H2O

What ultimately happens to the aminomethanesulfonate in the aquarium is not well established Even more complicated is the reaction of hydroxymethanesulfonate with chloramine, or chlorine (as Cl2 or HOCl). In this case, the products that are formed have not been established. 

, Sodium Hydrosulfite performs one of the following three roles: 

1. As a reducing agent, hydrosulfite chemically reduces other components by donating an electron or electrons. 

2. As a sulfonating agent, hydrosulfite adds sulfur to another chemical compound. 

3. As a cation source, hydrosulfite adds a cation, or sodium, to a product system increasing the conductivity and TDS

R


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## beaslbob (Oct 17, 2012)

rickey said:


> Seachem Priime is a reducing agent technically a complexed hydrosulfite salt (Sodium formaldehydebisulfite CH4O4S ) Sodium Hydrosulfite is a very strong reducing agent. A reducing agent is the opposite of an oxidant as it will reduce and or remove any oxidant such as chlorine, ozone, chlorine dioxide, just to name a few it will also remove oxygen. Other products, such as hydroxymethanesulfonate (HOCH2SO3-; a known ammonia binder can be used to treat chloraminated water because they both break down chloramine and bind up the ammonia.
> 
> The reaction of ammonia with hydroxymethanesulfonate is mechanistically complicated, possibly involving decomposition to formaldehyde and reformation to the product (aminomethanesulfonate). The simplified overall reaction is believed to be:
> 
> ...


Does that mean the pH goes down?




:lol:


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## rickey (Jul 7, 2013)

beaslbob said:


> Does that mean the pH goes down?:lol:


No, but I do think you want the chemist answer. When you use Prime the ammonia is converted to aminomethanesulfonate not to simple ammonium as it is with a pH shift.
I really a much more complex reaction that people realize. 

R


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## Hallyx (Jun 11, 2011)

It appears it is a great deal more complicated than Seachem's explanation of how Prime works. I wonder if they dumbed it down for us silly keepers, or if they really know what's going on. They say they're not sure how Prime handles nitrite.

Thanks for that explanation, Rick. I'm sure I'll understand it better if I reread it a few times.


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## beaslbob (Oct 17, 2012)

rickey said:


> No, but I do think you want the chemist answer. When you use Prime the ammonia is converted to aminomethanesulfonate not to simple ammonium as it is with a pH shift.
> I really a much more complex reaction that people realize.
> 
> R


 
Perhaps it is a secondary effect. Not directly caused by the direct chemical reactions.

In my case above there was a huge ammonia spike caused by my inadvertant addition of a toxin. The pH crash occurred about a week or two after treating with Prime and could have been part of the recycling as the tank recovered.


thanks for reply.

and my .02


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## rickey (Jul 7, 2013)

Patents # EP0203741A2

This will help a lot

R


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## Quantum (Jul 23, 2011)

something about this thread seems very familiar - same participants, same info


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## Hallyx (Jun 11, 2011)

I wholeheartedly disagree. Rickey is new, and his information is a great deal more detailed and accurate than anything we've seen here before.


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## pop (Aug 29, 2012)

Hello:
Not change the subject but do both forms of ammonia become inorganic nitrogen. If this is the case then inorganic nitrogen can be thought of as NH3 and NH4 and what is the difference between inorganic nitrogen and inert nitrogen from the atmosphere, in terms of usability? Is ammonia created from decay of organic substances a form of organic nitrogen and will all forms of nitrogen be used in plant photosynthesis? 

pop


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## jaysee (Dec 9, 2009)

Hallyx said:


> I wholeheartedly disagree. Rickey is new, and his information is a great deal more detailed and accurate than anything we've seen here before.


I agree with your disagreement 

Where I a chemist instead of a physicist, I'd be more interested in the equations and all. Certainly not information I've seen before, though. As for the same people - I think such an in-depth look has a limited appeal so that's not a surprise.


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## Hallyx (Jun 11, 2011)

This horse ain't dead enough for me.

So, even if Prime uses a more complex reaction to ionize (protonate?) NH3 into NH4 ---a way that doesn't effect pH--- doesn't the NH4 convert back to NH3 based on the pH? ie: lower pH = slower reaction; and higher pH = faster conversion to NH3. Then of course there's the temperature comsideration which is not marginal. 

The pH doesn't rise measurably (by me) when this happens. Does it go through that complex intermediary step as well?


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## Quantum (Jul 23, 2011)

I'll assume this is a serious question and also assume you would prefer it be answered by someone else, but the explanation is the same regardless of who gives it

the answer to your question is that it is not a simple ammonia to ammonium conversion

you seem to trust Rickey; he presented an equation in post #6 showing the (possible) reaction of Prime and similar products (understood to be Sodium Formaldehyde Bisulfite/Sodium Hydroxymethanesulfonate - synonyms for the same compound) with ammonia and neither of the products is ammonium

but you don't need to know any of the chemistry to come to the same conclusion, simple logic will do:

if the ratio of ammonia/ammonium is determined by pH and the mechanism by which Prime detoxifies ammonia does not effect or is not effected by pH, then one must conclude that Prime does not work by converting ammonia to ammonium


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## rickey (Jul 7, 2013)

pop said:


> Hello:
> Not change the subject but do both forms of ammonia become inorganic nitrogen. If this is the case then inorganic nitrogen can be thought of as NH3 and NH4 and what is the difference between inorganic nitrogen and inert nitrogen from the atmosphere, in terms of usability? Is ammonia created from decay of organic substances a form of organic nitrogen and will all forms of nitrogen be used in plant photosynthesis?
> 
> pop


 Inorganic nitrogen falls into 3 categories Nitrogen hydrides, Nitrogen oxoacids, and Inorganic amines. Nitrogen fixation is a process by which nitrogen (N2) in the atmosphere is converted into inorganic nitrogen (ammonia NH3). Molecular nitrogen is inert it does not easily react with other chemicals to form new compounds. Fixation free up the nitrogen atoms from the diatomic form. The biological fixation of inert nitrogen is carried out mainly by free-living and symbiotic Diazotroph bacteria although fixation occurs in some lightning strikes.

R


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## Hallyx (Jun 11, 2011)

Can't find the "Thank" button, sooo...

Thanks for the useful info, Rick.


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