sera Gravel Brown Lava consists of carefully selected, natural materials that are free of harmful chemicals and dyes. This makes it safe for all aquarium inhabitants, including fish, invertebrates and plants. Its special shape and structure also promote effective permeability and provide an ideal habitat for beneficial micro-organisms that contribute to biological filtration. In addition, Sera Aquarium Gravel supports plant health by providing a stable base for roots and allowing optimal nutrient circulation. This promotes plant growth and development, which in turn contributes to the overall quality and clarity of the aquarium water and minimises the risk of unwanted algae growth.sera Gravel Brown is CO2 proof and neutral towards water, i.e. it has no influence on water parameters and does not tint the water. It consists of ground lava rock, and provides ideal space for settling by useful bacteria due to being open and porous. It is thus effective as a supportive natural biological fi