Sand is the oldest and most popular method of in ground swimming pool filtration for swimming pools and spas. Water flows from the top of the pool filter to bottom laterals during normal filtration cycles. This bottom lateral system in the bottom of the pool sand filter then channels the water to return the clearly filtered water back to the pool or spa.
Swimming Pool Sand filters generally use #20 silica sand which is approximately .40 to .55 mm. As water passes from the top of the filter to the bottom particles of dirt and debris collect on top of and in the sand bed. The filter sand does need to be cleaned (backwashed) on a normal basis which reverses the water flow through the sand. After the filter is properly backwashed the filter is then "rinsed", which resets the sand, getting it ready for filtration. This is usually achieved with a multi-port valve on top of or on the side of the filter.
When installing this sand filter sand, always fill filter approximately 2/3 full with water prior to adding sand. Put sand in filter gently so as not to damage the sand filter laterals.
