JBL ManadoKey Features: Optimal plant care through porous structure and nutrient storage function: substrate for freshwater aquariums. Vigorous plant growth, prevents algae: effective settlement of beneficial soil bacteria and ideal root growth thanks to natural pore structure. Support for the filter. Crystal clear water. Ideal for fish, invertebrates and plants: no unwanted pollutants released into the water. Round shaped granule grains are gentle on sensitive