Calcium - one of the principal elements making up the earths crust, the compounds of which make the water hard. The presence of calcium in water is a factor contributing to the formation of scale and insoluble soap curds which are a means of clearly identifying hard water.
Capacity - an expression of the quantity of an undesirable material which can be removed by a water conditioner between servicing of the media, i.e., cleaning regeneration or replacement, as determined under standard test conditions. For ion exchange water softeners, the capacity is expressed in grains of hardness removal between successive regenerations and is related to the pound of salt used in regeneration. For filters, the capacity may be expressed in the length of time or total gallons delivered between servicing.
Carbon Dioxide - a gas present in the atmosphere and formed by the decay of organic matter;the gas in carbonated beverages; in water it forms carbonic acid.
Carbonate - the Co3- ion.
Carbonate Alkalinity - alkalinity due to the presence of the carbonate ion.
Carbonate Hardness - hardness due to the presence of calcium and magnesium bicarbonates and carbonates in water; the smaller of the total hardness and the total alkalinity.
Cation - an ion with a positive electrical charge, such as calcium, magnesium and sodium.
Cation Exchange - process in which cations in solution are exchanged for other cations from an ion exchanger.
Caustic - Any substance capable of burning or destroying animal flesh or tissue. The term is applied to strong bases.
Caustic Soda - the common name sodium hydroxide.
Chelating Agent - a chemical compound sometimes fed to water to tie up undesirable metal ions, keep them in solution, and eliminate or reduce the normal effects of the ion.
Chemical Oxygen Demand - the amount of matter, both organic and inorganic, in a water or wastewater which can be oxidized by boiling with a strong oxidizing acid under standard test conditions, and expressed as the equivalent amount of oxygen; often used as a measure of the strength of sewage and wastewater; includes materials not oxidized in the BOD test, and thus does not correlate with BOD.
Chlorine - a gas, widely used in the disinfection of water and an oxidizing agent for organic matter, iron, etc.
Chlorine Demand - a measure of the amount of chlorine which will be consumed by organic matter and other oxidizable substances in a water before a chlorine residual will be found; the difference between the total chlorine fed and the chlorine residual.
Coagulant - a material, such as alum, which will form a gelatinous precipitate in water, and cause the agglomeration of finely divided particles into larger particles which can then be removed by settling and/or filtration.
Coagulant Aid - a material which is not a coagulant , but which improves the effectiveness of a coagulant, often by forming a larger or heavier particles, speeding the reactions, or by permitting reduced coagulant dosage.
Coagulation - The process in which very small, finely divided solid particles, often colloidal in nature, are agglomerated into larger particles.
Colloid - very finely divided solid particles which will not settle out of a solution; intermediate between a true dissolved particle and a suspended solid which will settle out of solution. the removal colloidal particles usually requires coagulation to form larger particles which may be removed by sedimentation and/or filtration.
Compensated Hardness - a calculated value based on the total hardness, the magnesium to calcium ratio and the sodium concentration of a water. it is used to correct for the reductions in hardness removal capacity caused by these factors in cation exchange water softeners. No single method of calculation has been widely accepted.
Conductance - a measure of the ability of a solution to carry electricity, the reciprocal of the electrical resistance. The unit of conductance is the mho(reciprocal ohm).
Conductivity - the quality or power to carry electrical current; in water, the conductivity is related to the concentration of ions capable of carrying electrical current.
Corrosion - the destructive disintegration of a metal by electrochemical means.
Cycle - a series of events or steps which ultimately lead back to the starting point, such as the exhaustion-regeneration cycle of an ion exchange system; sometimes incorrectly used in reference to a single step to a complete cycle.