Sera Crystal Clear Professional high performance mechanical filter media quickly removes even the smallest of particles. The innovative, patented, design allows these balls of fiber to retain their shape, even through rinsing and reuse. As with any mechanical filter media, the efficiency declines a little with each reuse, but with only a 20% decline in effectiveness you are sure to get your moneys worth out of this media. Use with Sera's Siporax biological media for professional results out of almost any filter.