It is designed for better shape & size It is mechanically & Biologically, effective filter material Enormous porous surface area is the ideal culture medium for micro-organisms, therefore, it produces out-standing filtration results * Strongly recommended to use with Ocean Free A-Z Super Beneficial Bacteria, Bio-Zyme, Activated Carbon, Bio-Foam, Super Zeolite Crystal, Bio-filter pad, FilterWool, Bio-plate or Bio-Ball for Best results.