AstralPool 06681 55" Diameter 16.58 SqFt Vertical Commercial Sand Filter with 4" Flange. AstralPool Vertical Commercial Sand Filters are constructed in Jacksonville, Florida. Filters hold an NSF listing for a working pressure of 50psi and a test pressure of 75psi. Man-Way is a diameter of 16 Inch. Filters are constructed in six reinforced layers of laminated and filament winding. AstralPool offers a vast range of Vertical Filters of surface areas. Filtration depths of 2 ft on Short Series, 3 ft on our Standard Series and 4 ft on our Deep Bed Series. Multiport Valves, Standard and Custom manifold systems, Semi and Fully Automated Systems, Sand and gravel required and sold separately