Volcanic stone commonly known as pumice stone, basalt stone, or lava rock, it is a kind of functional and environmental material. It contains dozens of minerals and microelements, which are widly used to garden, floor, wall, plant, acqurium industry.

1. Appearance and shape: no sharp granular, low resistance to water flow, not easy to block, uniform water and air distribution; rough surface, fast film coating speed, and the microbial film is not easy to fall off during backwashing.
2. Porosity: volcanic rock is a natural honeycomb porous, which is the growth environment of mycelium.
3. Mechanical strength: 7.08Mpa by the quality inspection department. The practice has proved that it can withstand hydraulic shearing of different strengths, and its service life is much longer than other filter materials.
4. Density: The density is moderate, it is easy to suspend and does not run out during backwashing, which can save energy and reduce consumption.