# Does anybody tried KOH?



## Christian_rubilar (Jul 21, 2005)

How do i know the dosis? Thanks (I know the risk of preparing the solution from the dry compound, I also know that it is letal if is eaten and burns if you touch it)


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## Edward (May 25, 2004)

Christian_rubilar said:


> I also know that it is letal if is eaten and burns if you touch it)


 KOH has a pH of 13.5. What do you think your fish would do?


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## slickwillislim (Oct 11, 2005)

Its a strong base. To get any significant amounts of K your going to have to add quite a bit of OH-. I would not try this. Strong acids and bases are dangerous to work with and hard to control in your tank.


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## Christian_rubilar (Jul 21, 2005)

Okidoki, I have some friends from chile who use potasa, they told me that it is K2O. I undertand that K2O becames KOH when gets humidity. They told me that using potasa they were able to add more k without algae and plants became strong enough that a scissors was need to cut them.
Edwards, I wrote "(I know the risk of preparing the solution from the dry compound, I also know that it is *letal *if is eaten and *burns if you touch it*)" because i already read about KOH and I found prudent to clarify it acording to the high risk of using that salt.
Thanks


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## Revan (Dec 26, 2005)

Plants became strong if they have all of what they need, not only potassium

Generally it's better avoid to use strong bases or strong acids because they are dangerous to manipulate and they may be harmful for fish

Best Regards


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## SuRje1976 (Mar 3, 2006)

Christian, are you sure it is actually K2O they are using? K2O is quite rare, and not commonly used in fertilizers. K2O IS however, comminly used to describe the amount of bioavailable potassium in a fertilizer product, even though the postassium comes from another source, such as K2SO4. Actual K2O reacts pretty violently with water, and wouldn't be practical for use in an aquarium.


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## Squawkbert (Jan 3, 2007)

KOH - very dangerous stuff, not at all good for aquariums. If concentrated, it can burn/dissolve flesh, will react quite violently and exothermically with water.


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## Christian_rubilar (Jul 21, 2005)

Thank you Squawkbert. Don´t worry, i don´t take any risk. If KOH can be use to add K without nothing else, then there are safe ways to get a diluted solution. One can be to pay a chemistry company to prepare it. Usually, the pipes cleaning products use KOH and NaOH. I can visit a factory of this "strong cleaners" and buy some liters without NaOH.
SuRje1976, well, K2O can be rare, I don´t doubt it. The reazon is that as soon as it gets humidity becames KOH. Remember that in Chile they have natural resourses of potassium salitre and they produce potasa from this guano, bird and bats detritus. But i think that natural potasa is not as concentrated and dangerous as the industrial KOH. 
Revan, yes, no, so and so. I was talking about a fact no theory. Using potasa my friend got extremly strong plants without curling leaves. 
The problem is that i can´t find the potasa he use (KOH already diluted in water or natural unconcentrated, i don´t know) in my country.
Thanks for your answers


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## gacp (Sep 11, 2006)

Would potasium carbonate, K2CO3, work?


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## Christian_rubilar (Jul 21, 2005)

Gustavo, the idea is to add potasium without any partner. When you use too much potasium carbonate the plant gets black becouse of a kind of red algae. Too much doesn´t mean a lot but the KH problem is another subjetc (Gustavo and me have Kh 1 at Buenos Aires City).


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## gacp (Sep 11, 2006)

Christian_rubilar said:


> Gustavo, the idea is to add potasium without any partner. When you use too much potasium carbonate the plant gets black becouse of a kind of red algae. Too much doesn´t mean a lot but the KH problem is another subjetc (Gustavo and me have Kh 1 at Buenos Aires City).


Christian, I don't get that. Isn't carbonate, C03,2-, just the product of CO2 and water? And isn't KH a measure of the concentration _calcium_ and _magnesium_ carbonates? But we'd be adding no calcium and no magnesium! Just K, and CO2 as carbonate as the 2 are in equilibrium with bicarbonate in aqsol:

CO3,2- + 2 H2O <-> HCO3,1- + OH1- + H2O <-> H2CO3 + 2 OH1-
CO2 + H2O <-> HCO3,1- + H+

And, if we were to add KOH, wouldn't we get potassium carbonate anyway?

CO2 + 2KOH <-> K2CO3 + H2O

I guess we would be increasing the KH, but is that bad? (At least in Baires, with KH=1).

Chemistry is far from my cup of tea


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## Revan (Dec 26, 2005)

You are right but KH test kits don't measure KH but alkalinity and then convert the alkalinity (generally measured in meq/l) in °dH (german degree of hardness).
The KH test kit contains an acid (generally HCl) and a pH indicator that change color when the pH value goes below 4.3
So every drop of the reagent add HCl and lower del pH value. When all CO3-- and HCO3- became H2CO3 the pH value go below 4.3 and so you have the value of the alkalinity.
So K2CO3 don't modify the value of the KH but modify the value of the alkalinity that is what you measure with a KH test kit

It is why if you add NaHCO3 to RO water you can read from a KH test kit a KH value greater than GH (if bot are measured in °dH) because KH tests kit measure alkalinity and not KH. If you can measure the true value of KH if you add NaHCO3 to RO water KH remains to zero and always the KH value is lower than GH value (that measure all Ca and Mg salts and not only Ca or Mg carbonates and hydrogencarbonates) but all the KH test kit measure alkalinity and alkalinity may be greater than GH.

The "principle of conservation of Alkalinity" shows mathematically that the total alkalinity of a sample cannot be changed by adding or subtracting CO2

If you want to read a good article about alkalinity follow this link:
http://www.advancedaquarist.com/issues/feb2002/chemistry.htm

I'm sorry for my bad English

Best Regards


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## kekon (Aug 1, 2005)

> Could potasium carbonate, K2CO3, work?


Don't use it !!! I used it for some time (and some of my freinds as well) but it caused terrible stunting. It has very high pH (12..13) and raises KH quickly. It seems it causes damages in plants tissues. Don't confuse K2CO3 with KHCO3. KHCO3 is a very good source of potassium and 10% solution has pH of about 8 and plants do love this compound.


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