5. REGULATION OF THE CARBONATEHARDNESS

A test stick was dived 5sek. into the aquarium water. After 30sek. we read off the color.
The developed color (green), was compared with the imprinted colors and the pertinent units on the test stick packing. The color (green) results 6°d.

If 1°d = 1,8°f = 1,25°e = 17.8 mg l CaCO3 -->106.8 mg l CaCO3;
therefore 6°d = 640.8 mg l CaCO3.

Formulas:
Carbon dioxide: CO2
hydrogencarbonate - ion: HCO3 (simply negatively charged)

How depends the pH value of the concentration of solved carbon dioxide?
Carbon dioxide and water react to carbonic acid.
The developed carbonic acid reacts with the water again to a hydrogencarbonate ion and a Oxonium ion.

Reaction: CO2 + H2O --> H2 CO3 H2 CO3 + H2O--> HCO3 H3O (simply positively charged) Remark: The Oxonium ion is responsible for the sour characteristic of the water.

Thus the more CO2 reacted with water the more sourly is the characteristic of the water.
The CO2 is decisive for the process of the following reaction.
The whole expiration runs like a mechanism .

By which procedures is the concentration of the carbon dioxide in the aquarium water affected?

The fish in the aquarium breathe out CO2.
The plants need the CO2 again during the photosynthesis procedure to manufacture with the assistance of the water materials with high energy.
During this procedure it develops oxygen, which is important for the fish;
because they inhale CO2; while they' re breathing out CO2 afterwards.
This mechanism benefits all the organisms in the aquarium.