... in the water treatment hard duarble,high quality Garnet Sand filter material ItemDataItemDataSpecific gravity3.9g/cm3Acid endurance96%Volume weight2.5g/cm3Porosity47 ... 4mm,3-6mm,4-8mm,5-10mm Gravel and water filter pebble is composed of sub-angular,hard durable ,and ... finest availble in the world for water filtration applications.Our filter gravel is washed,clean dried,and screened to meet exacting ...