The manufacturer informs:

It is a filter material, i.e. a substrate for bacteria (bacteria in the aquarium filter are used to decompose fish excrement and to eliminate the very potent poisons created during organic decomposition). As the concentration of decomposing organics in an aquarium is very high in relation to the amount of water, it is obvious that we need a very consistent and very active bacterial culture. Since these bacteria are bound to a substrate, it is obvious that this substrate must be as large as possible.

The effectiveness of a filter in an aquarium depends solely on the ability to provide optimal conditions for the settlement of bacteria.

• Highly porous sintered glass rings for settling filter bacteria in internal or external biological filters for aquaria and ornamental ponds.
• Very high filter surface area (over 500 m² per litre of product)
• Very long life
• Dimensions: mm16 x 15 in diameter
• Does not release harmful substances