... filter material, ceramic sand filters have great advantages as follows:1. Shaped in sphere, the ceramic filter sand has a high void ... entrapment, up to 9-10 kg/m3, about 1.2 or 1.5 times that quartz sand filter of 7.8 ... Particle size,mm0.5-3.0- Bulk density, g/ml1.1-1.5-Free volume,%40-45- Abrasion resistance,%≤0.5- Compressive ... for 14 days 4. Product Size(mm):Φ0.5-1,Φ1-2,Φ2-3,Φ5-6,Φ6-8,Φ8-10,Φ10 ...