1.They are made of quartz sand(SiO2) with ring form and polyporous structure which can decompose the pollutant efficiently.It is suitable for freshwater and saltwater aquariums.
 

2.Double filtration efficacy can be used to filtrate the crude molecular particles as the first mechanical filtration or as a biological filtration.The filtration system can be kept unobstructed by the first filtration.
 

3.The polyporous structure creates an ideal environment for the growth of beneficial bacterium  while supplying good water flow rate.
 

4.Large and effective specific surface area is preferable for the implantation and propagation of beneficial bacterium