Special nested-porous structure enables higher proliferation rate of aerobic probiotic, which rapidly builds up nitrification system. Keep up the water quality in crystal clear condition. Water content and water absorbing capacity greatly surpass other porous bio balls. Pores spread evenly throughout whole unit; pores per surface area are 10 times more than general products on the market. For general products, the pores only scatter on surface, no poress exist inside.