George Solt CEng, FIChemE, in Plant Engineers Reference Book (Second Edition), 2002. 19.7.2 Sand filters (Depth Filters). Sand filters are widely used in water purification and remove suspended matter by a completely different mechanism. Instead of the water passing through small orifices through which particles cannot pass, it runs through a bed of filter medium, typically 0.75 mm sand 750 ... Mar 08, 2013 The Day We Switched Polymeric Sand. Hi everyone, this is Jeff Pozniak writing todays note about the death of a polymeric sand. For those of you who dont know, polymeric sand is a coarse, dried sand that has had polymers added to it that when activated with water, harden up and seal off paver joints (the seams between each paver).