1. Bio sponge provide mechanical and biological filtration, trap large amounts of waste, and do not clog easily. The size of the pores is measured by the number of pores in the unit area (PPI), the higher the PPI, the more pores in the sponge. It is recommended to use a combination of different size sponges for the best effect. 2.Dye-free and safe for aquatic pets. Bio sponge is usually used as pre-filters for wet/dry filters, catch basins, and tank filters. 3.Regular cleaning. Reusable and durable after cleaning. 4.We are a competitive manufacturer in the aquarium field. We are mainly engaged in the development, production and sales of aquarium filter media and various aquarium accessories. Our main products are: sponge filter, bio sponge, Japan mat, filter brush, bio ball, ceramic rings, active carbon, air stone, etc. We can produce products of various sizes, shapes, and colors according to your needs. Samples or drawings are welcome.