1 bag has 502 surface area. ECO-Pondchip Power your Filter … The Eco Pondchip is a new development in (moving bed) filter media. The ECO Pondchips have their origin in the professional waste water treatment, but they have been further developed for usage in ponds. The green chip has a diameter of 20mm and is 1mm thick. The unique surface structure has a specific surface area for bacteria of 3500m²/m³- what is in average 5-7 times bigger than traditional bio-rings. As a result you need less of these chips than traditional bio rings. The Eco pondchips are made of virgin, food grade PE and do not include recycled materials. The Eco pondchips are very light, so you don´t need much energy to move them (by air and/or water). This can significantly reduce the energy costs of air pumps. Usage: The Eco Pondchips are used as a biological filter medium (after a mechanical pre-filter). The filter chamber can be filled up to 60% with Eco Pondchips. The chips can also be used as extension for existing moving bed media. As a result the biological filter capacity is upgraded without further reconstruction. Eco Pondchips come in mesh bags with approx. 14 litres of chips. These 14 litres have a surface of 50m² for bacteria, which is sufficient for an average fish load in 20m³ pond water. Since this media initially repels water, it is recommended to hang the bag in the pond/filter for a couple of days, before they are put into the filter. 50m² (±14 litre) in filternet bag (for 20m³ pond water).