This has been applied to the determination of low level Cu(II) in specialized plating baths, and to the determination of total hardness in water.

The new directive saw the number of parameters reduced whilst allowing member to add parameters such as magnesium, total hardness, phenols, zinc, phosphate, calcium and chlorite.

Currently, total hardness is defined as the sum of the calcium and magnesium concentrations, in milligrams per liter, expressed as calcium carbonate.

The pH value is 6.1, the average dissolved oxygen 10 p.p.m., and the total hardness (SBY) 2.4.

The total hardness of the control should be comparable to the receiving water.

The sum of this two is called total hardness and expressed as PPM.

Ensure hardness levels are suitable for fish species that you are keeping, although most will tolerate a total hardness of between 100-250 ppm.

The difference between this and the total hardness then gives the magnesium content.

The morphology,physics,chemistry and biology measure high pH, conductivity and total hardness.

Sodium carbonate (washing soda) further reacts with the remaining Ca and Mg in the water to remove / precipitate the total hardness.