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Ακης

Dissolved Solids:

Total dissolved solids (TDS) is a measurement of the total amount of dissolved substances in water and expressed in ppm of NaCl. TDS is essentially the same as conductivity. For aquarium applications it is recommended that the conversion formula TDS (in ppm) × 0.64 = EC (in ΅S/cm) be used. The conversion formula is only an approximation. TDS meters are calibrated with a Sodium chloride solution.
Conductivity or specific conductance is the measure of the water's ability to conduct an electric current. Conductivity depends upon the number of ions or charged particles in the water. The specific conductance is measured by passing a current between two electrodes (one centimetre a part) that are place into a sample of water. The normal unit of measurement for conductivity is expressed in microsiemens per centimetre (΅S/cm) or millisiemens per centimetre (mS/cm) . Conductivity meters are calibrated with a Potassium chloride solution.