HARDNESS
Hardness is caused by divalent metallic cations Ca2+ and Mg2+contact with soil and rock formation.CO2 dissolve in water and develops low pH dissolve the hardness forming materials.Total hardness of water is classified to metallic ion and anions associated with the metallic ions,also (total hardness =non-carbonate+carbonate hardness）
EDTA titrimetric method is to determine hardness while ERIOCHROME BLACK is the colour indicator.The end point of titration is the colour change from reddish pink to blue then total hardness can be found.
NITRATE-NITROGEN
NH3 is oxidized to nitrates by bacteria and produced by direct oxidation of nitrogen.Nitrogen compounds are released in the waste products of the body of fish.It is determined by spectrophotometry.Nitrate-N reacts with NITRAVER5 NITRATE REAGENT to form a coloured product.The intensity of colour formed depends on the concentration of coloured product formed,in turns to depends on the concentration of nitrate-N.
