Article pH, kH and gH

Start:
PH = Exact definition is not known. I was only able to find this meaning: "the power of hydrogen".
KH = Carbonated hardness
GH = Total hardness

the link between these parameters is very complex. We would probably take years to determine accurately an equation with those 3 unknown.

Water hardness is temporary and permanent.

The first element that must be taken into consideration, in an aquarium, is total or permanent hardness of water. It accumulates, by definition, the quantity of calcium and magnesium ions that can be found in water, in the form of bicarbonate and / or sulfur (CaCO3, CaSO4, CaMg) (CO3) 2 - limestone (calcite, aragonite, marble, or chalk, sulfate calcium and dolomite). Total hardness is defined as 10 mg of calcium oxide per liter of water, which is exactly 1 degree German (17.848 ppm or 17,848 mg / L CaCO3). We now ask what is included in the Mg measurement. The answer is: the nature of water hardness (which contains both Ca and Mg in the form of ions) which is usually expressed in equivalent concentration of pure calcium dissolved in solution. For example, water containing 1.5 milimols / liter calcium (Ca ions) and 1.0 milimols / l Magnesium (Mg ion), is equivalent to a hardness of 2.5 milimols / liter solution of calcium (exclusively), i.e. 250.2 is equal to 250.2 ppm mg / l of calcium (Ca).

Thus we have different types of total hardness:
- very soft: 0-70 ppm, 0-4 dGH
- soft: 70-140 ppm, 4-8 dGH
- slightly hard: 140-210 ppm, 8-12 dGH
- medium: 210-320 ppm, 12-18 dGH
- hard: 320-530 ppm, 18-30 dGH
- very hard: > 530 ppm,> 30 dGH

- Dropping the GH can only be made using osmosis equipment or RO (reverse osmosis).
- Increasing the GH can be done by adding the 2 salts to the water, calcium and magnesium. As a solution of calcium you can use chalk, lime, or broken coral. For the Magnesium, you can use Epsom Salt.
The quantity required for Mg cannot be specified (only possible in the laboratory) by the simple fact that we do not know of the quantity that is already in the existing water. Adding is done under close observation of GH parameter.

The 2nd parameter is the temporary hardness or carbonated hardness (most important parameter in my opinion).
It defines the amount of CO3 or HCO3 (bicarbonate and carbonates) in water (17,848 mg or 17,848 ppm of calcium carbonate (CaCO3) per liter of water in a high German KH).





- Increasing the KH can be done by adding carbonate / bicarbonate in the water. We can successfully use acid sodium carbonate (bicarbonate) NaHCO3 (baking soda). By dissolving it, the result is sodium carbonate (Na2CO3) + CO2 + H2O. Adding should be done under careful observation due to the fact that it will alter the waters pH. The cause is the following: NaHCO3 hydrolysis (reaction of sodium ions (Na) in NaHCO3 with salt H2O), resulting in a base, a weak base (Na2CO3). Also potassium can be used as a bicarbonate (KHCO3), (harder to find and more expensive) with the same terms as in the case of sodium bicarbonate, with mention that potassium ions that result can be used as fertilizer for planted tanks .

- Dropping KH is done by adding an acid in very low concentration directly to the water. The most commonly used is sulfuric acid (H2SO4) in concentrations up to 0.6%, under careful observation. Another method of reducing the KH and GH is the myth of boiling water and then allowing it to cool or by adding lime (calcium hydroxide - CaOH). The reaction is the following: boiling leads to the formation of carbonate / bicarbonate in the form of precipitation and carbonate / bicarbonate into the calcium solution, resulting in a soft water when it's cooling. The reaction steps are: boiling, precipitation, cooling, and constant temperature. At this moment the reaction begins to reverse. The reverse is the process of the dissolution and reaching the initial phase, which has left for boiling…noting that in this case with adding lime that the GH will increase. The end result of water with the same KH at the beginning, but with higher hardness. The solution is to stop the process when water reaches a temperature of 45-50 degrees, decanting the solution (water), sudden cooling, and decanting the final. Precipitation amounts will be nearly invisible to naked eye (milligrams), or in some cases ... who knows ... will submit rocks.




The PH

PH is a parameter that measures the acidity or alkalinity in a solution. It is a logarithmic function of the hydrogen ions dissolved in solution at a moment in time. The PH scale ranges from 0 to 14. Beginning with: 0, hydrochloric acid (HCl) and ending with 14, sodium hydroxide (caustic soda - NaOH). As a logarithmic function in ten bases, the difference of 1 unit of pH between 2 solutions means a tenfold difference between the 2. Example: A solution of pH 6.6 as A and solution pH 6.7 as B. Solution A is ten times more acidic than solution B. The acidity or alkalinity of a solution is the amount of acids or salts dissolved in that particular solution, therefore back to the KH. We have said that his grades means a quantity of salt dissolved in water. Therefore the relationship between the KH and PH is very close. It reticulates that the KH acts as a buffer for the PH, which is true. The question to ask is "why". The answer is simple. Take example sodium bicarbonate:
1. 2NaHCO3-> Na2Co3 + CO2 + H2O
2. CO2 + H2O-> H2CO3
3. H2CO3 + H2O-> H3O + HCO3
4. Na + HCO3-> NaHCO3
Now to explain the responses above. As you can see there are reactions that occur cyclically and in chain under the action of certain factors (temperature, consumption and production of oxygen consumption, and CO2 production). By dissolving bicarbonates in water we obtain sodium carbonate (PH increases), CO2 and water. CO2 and water forming carbonic acid then (the weak acid - H2CO3 - but lowers PH). Water and carbonic acid releases the 2 ion, hydrogen carbonate (HCO3) which is alkaline and acid at the same time, and the hidronium ion (H3O) which is essentially water and hydrogen, H2O + (H +). At this point, we see the free ion of hydrogen responsible for the PH. Sodium hydrogen carbonate and the last reaction leads us to bicarbonate at the start of experiment.



-Changing the pH can be done only through the evolution of KH, due to acid or alkaline. The adjustment is done gradually, not suddenly, from close modifications of no more than 1 degree KH a day. After bringing the PH value to the desired increase / reduction and depending on KH as needed…An optimal value is 4-6 degrees for any type of tank, sterile or planted. Addition of CO2 in water, bombs or professional, results in the production of carbonic acid in water (H2CO3 - reaction 2) without introducing a salt into the tank water. Therefore the reaction is only going down, it is not cyclical, and it is dissolution and assumes the existence of carbonate in the water. Their absence leads to the production of acid much more dangerous than carbonic acid and the sulfuric water is turned into a highly acid environment resulting in irreparable losses.

Article Written By: catatataee