Red Sea Max 130/D - Filter Sponge.
This coarse sponge offers both mechanical and biological filtration. Simply add to the filter in your Red Sea Max aquarium.
The coarse material will trap debris and dirt whilst allowing the best flow of water through its porous surface.
The porous texture of this sponge also allows for the best development of bacterial colonies. This creates biological filtration. Remember to rinse the sponge in old aquarium water so as not to destroy established bacteria.