Traditionally Pressure Sand filters are used for filtering swimming pool water for trapping suspended & coagulated impurities. Pressure sand filters use multi grade silica sand as a filter media. Normal life of these media is 5 to 7 years.
For private swimming pools , the re-circulation water filtration velocity is around 35 40 m/hr. For all other swimming pool, especially public swimming pool filtration velocity is 30 35 m/hr.
Advantage of these type of filter is, they can be repeatedly used after backwash. When pressure difference increases by 7 psi (0.5 Kg./cm²) than initial service filter pressure, sand
Payback time considering filter cleaning waste water is less than 1 year.