Erosion is the wearing away of material by physical and chemical forces. For example, storm water can erode farm lands and wind erodes dry soil and rock. A coupon is a small section of metal inserted in a water line to test for corrosion or scaling rate of a water system. Hardness refers to a characteristic of water primarily caused by calcium and magnesium salts. The Baylis curve shows the relationship between the pH and the alkalinity of the water and provides a tool for establishing chemical feed rates in order to avoid deposition and corrosion.
Drift is a change in an instrument reading over a change in time.
All measuring instruments have drift and must be re-calibrated in accordance with time to a standard to provide reliable results. Hysterersis is the phenomena of having two different readings as opposed to the standard or known in the same instrument when the values are measured from opposing ends on a scale. Density is the mass of an object divided by the volume. Conductivity is the ability of a substance or material to carry or transmit an electrical current. Volume units are given in cubes such as cubic feet or cubic meters.