The dosing of chlorine in the form of hypo is always expressed in:

•	PPM (parts per million) or mg/litre chlorine. Both represent exactly the value e.g. 2 PPM = 2 mg/litre chlorine, and,
•	total and residual chlorine, where total chlorine is the dosing at the point of application, and, residual chlorine is the remaining chlorine level after a certain time period of oxidation

The level of chlorine dosing depends on the client’s needs and will vary according to specific conditions and objectives

Typical hypo dosing and control methods:

•	pump types: metering (piston or diaphragm), or, centrifugal magdrive dosing pumps
•	quantity of dosing pumps: 1x 100%, or, 2x 100% hypo (a duty and standby pump)
•	dosing control: proportional flow, or, programmable on-line residual Cl2 control
•	continuous and shock dosing (required for anti-biofouling i.e. in sea water applications)