Shrimp King Active SoilKey Features: The irregular shaped grains, with a diameter of 1 4 mm also give a natural appearance The dark black colouring provides excellent contrast with the vibrant colours of the shrimps Porous surface for the settlement of important cleansing bacteria Also extremely well suited to use with substrate filter systems Does not discolour water Promotes growth bacteria, single cell organisms, single cell algae and other microorganisms as valuable,