Pressure Sand Filters These are the most conventional filters and are in extensive use. The filtering media in these filters in coarse & fine Sand (16/32 mesh). The sand is normally supported on a bed of graded pebbles. Under bed can be replaced by strainers also. In case strainers are provided, 100 mm layer of crushed coarse & fine silex is provided so that the fine sand dose not Clog the strainer buttons.