In order to achieve and maintain a biological balance in the pond, it is necessary to provide the pond with a good substrate. This premium pond substrate fulfills all the requirements that a good bottom layer should have. The material is highly permeable to air, which creates an enormous internal surface area that is so important for the bacteria and micro-organisms that are essential for the pond. This makes it ideal for biological filters. The material is also ideal for growing pond plants. The biological effect of this material also helps to prevent algae problems. It prevents the accumulation of bottom silt and promotes the growth of pond plants. For a good biological effect, it is important to spread the material evenly over the bottom in a layer approx. 2 cm thick.