Swimming Pool Sand Filter with suitable flow rate

Guidance on the design of rapid sand bed filters suggests that they should be operated with a maximum flow rate of 9 m3/m2/hr.Filtration and backwash rates are calculated by dividing the flow rate through the filter by the surface area of the filter bed. Typically these rates are measured in gallons per minute per square foot of filter bed area.The circulation system and backwash piping shall be adequate for proper backwashing of said filter and shall provide backwash flow rates of at least 12 gpm per square foot (0.8 L/s) or rapid sand filters or 15 gpm per square foot (0.9 L/s) for high rate sand filters.High-rate sand filters have a filter rate of 15 to 20 gallons per minute per square foot of filter area. They also work on the basis of depth filtration. The dirt removed from the water is not collected on top of the sand bed but is driven into the sand bed by the high velocity of the water.