OASE AquaActiv PondLith is a zeolite-based filter material. Zeolite is a natural type of rock with a crystalline surface approximately 1000 times larger than sand or gravel and is therefore ideally suited as a filter material. OASE AquaActiv PondLith has a grain size of 5 to 10 mm. Microorganisms settle on the large surface area, binding and breaking down excess nutrients. This improves the water quality in a natural way and counteracts the growth of green algae and water turbidity. The high-quality filter material is available in a practical filter basket (20 × 20 × 12 cm) with a capacity of 2.5 kg, sufficient for 2500 litres of water. The filter basket with the filter material is simply placed in the water or the filter system. The duration of action after initial use is 125 days.