This highly porous sintered glass medium is ideal for biological filtration. With a huge surface area in excess of 1,000 square metres per litre, less medium is needed to filter the pond. Its hooped shape ensures water flows through unimpeded and does not bypass it. It is inert and will not affect the water chemistry.
Two pack sizes, 0.5litre (1218, packed for aquarium use but is also suitable for ponds) and 2.4kg.
