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Water Hardness Level

Effect of calcium carbonate (CaCO3) in water can also be expressed as the hardness of the ability of water to form foam when mixed with detergent (soap). On the water has a low hardness will easily form foam when mixed with soap. While on the water that has high hardness would not form foam. Hardness is very important for the life of the fish. Not all fish can live in the same hardness value.

In other words, every kind of fish require hardness value in a certain range for his life. In addition, the hardness is also an important clue in conjunction with efforts to change the pH value. Hardness is a measure of the amount of calcium ions (Ca2 +) and magnesium ions (Mg 2+) in water. Other ions actually being similarly affect the hardness value, but its influence is very little known and relatively difficult to measure so it gets ignored.

Hardness is generally expressed in ppm (parts per million or one per million parts) of calcium carbonate (CaCO3), hardness (dH) or by using a molar concentration of CaCO3. One unit of hardness dH German or equal to 10 mg of CaO (calcium oxide) per liter of water (10 ppm). In America, hardness generally uses ppm CaCO3, thus one unit of Germany (dH) can be expressed as 17.8 ppm CaCO3.

While the molar concentration units of 1 milli equivalent = 2.8 dH = 50 ppm. It should be noted that most teskit measuring hardness using the unit CaCO3. Here are the criteria commonly used hardness range:

  • 0-4 dH, or 0-70 ppm CaCO3: very low (very soft)
  • 4-8 dH, or 70-140 ppm CaCO3: low (soft)
  • 8-12 dH, or 140-210 ppm CaCO3: medium
  • 12-18 dH, or 210-320 ppm CaCO3: rather high (rather loud)
  • 18-30 dH, aau 320-530 ppm CaCO3: high (hard)

Incompatibility hardness will affect, among others; transfer nutrients (nutrients), the secretion through the membrane, fertility, the function of internal organs (such as kidneys, circulatory and others) and growth. Each type of fish requires a certain hardness range for his life. In general, almost all types of fish and plants can adapt to the conditions existing hardness. But on the spawning process may fail when performed on the hardness value is not appropriate.

Hydrogen Sulfide (H2S)
H2S is highly toxic to aquatic biota. Under anaerobic conditions heterotropic bacteria can utilize sulfate (SO4 =) and excreting in the form of sulfide (S =).
SO4 + 8 H + -> S + 4 H2O (heterotropic bacteria)
H2S  -> HS + H +
HS -> S = + H +
For the development of egg hatching and larval development of the concentration of hydrogen sulfide (H2S) must be less than 0,019 ppm. Juvenile does not exceed 0,045 ppm H2S, while the adult does not exceed 0.048 ppm H2S.


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