# Citric acid directly into the tank



## micheljq (Oct 24, 2012)

Good morning, just a quick question.

If citric acid is poured directly into a tank in small amount. Will it react with the KH in the tank and produced some co2? I know it will lower pH at least temporarly.

Thank you,


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## jeffkrol (Jun 5, 2013)

micheljq said:


> Good morning, just a quick question.
> 
> If citric acid is poured directly into a tank in small amount. Will it react with the KH in the tank and produced some co2? I know it will lower pH at least temporarly.
> 
> Thank you,


don't think it works that way..


> Citric acid is H3C6H5O7, and it is tempting to think that some of those carbon and oxygen atoms in that molecule might become molecules of carbon dioxide. They can, but not in a reaction with sodium bicarbonate (acid-base). If you react citric acid with oxygen (combustion), then you can produce carbon dioxide.





> Bicarbonate anions react with protons from acid to produce carbonic acid, which decomposes to form carbon dioxide:


http://chemistry.stackexchange.com/questions/34898/baking-soda-citric-acid-water-co2-how-much-though


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## GrampsGrunge (Jun 18, 2012)

The amount needed to actually spike up the CO2 would also cause some big and fast pH changes.

Which wouldn't be good for the fish or plants.


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## Bunsen Honeydew (Feb 21, 2017)

jeffkrol said:


> don't think it works that way..
> 
> 
> http://chemistry.stackexchange.com/questions/34898/baking-soda-citric-acid-water-co2-how-much-though


The way I read the OP, was that the citric acid would be a proton source to react with the carbonate/bicarbonate already in the aquarium.

As an aside, citric acid will decarboxylate to give an equivalent of CO2, but not at temps that are amenable to aquarium conditions.


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## micheljq (Oct 24, 2012)

Ok thanks for the replies, then why the diy co2 with baking soda and citric acid works?

I must agree that dosed directly in the tank, the pH down spike can be dangerous.

Michel.


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## natemcnutty (May 26, 2016)

micheljq said:


> Ok thanks for the replies, then why the diy co2 with baking soda and citric acid works?
> 
> I must agree that dosed directly in the tank, the pH down spike can be dangerous.
> 
> Michel.


Think about purity and concentration of the contents in your bottles as compared to what is in your tank. Even if you had RO water with nothing but baking soda in your tank, dumping citric acid in there would just off gas a bunch of CO2 immediately in one big reaction. There's a reason they are kept in separate bottles with pressure held by a regulator


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## jeffkrol (Jun 5, 2013)

micheljq said:


> Ok thanks for the replies, then why the diy co2 with baking soda and citric acid works?
> 
> I must agree that dosed directly in the tank, the pH down spike can be dangerous.
> 
> Michel.


As far as I understand it.. it is the baking soda that liberates CO2.. Could probably use other acids than citric and get the same amount of CO2....


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## Bunsen Honeydew (Feb 21, 2017)

Also, reaction kinetics are proportional to the concentrations of the reactants. Because of that, the increased volume of the whole aquarium would make the same amount of acid and bicarb react slower.

Other acids could certainly be used, but citric acid is a triacid that is fairly efficient with respect to acid equivalents to weight, and because it is available as a crystalline solid, it is easier to handle and less likely to burn you with contact or fumes.


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