A one chamber filter system including filter media for the filtration of pond water. The water flows into the box through filter foam and a net with Filtra-Sub.Compact box filter for pondsFilter foam removes coarse dirt particlesFiltra-Sub for excellent biological filtrationin the set: pond pump for the circulation of pond waterin the set: filter hose to connect the pump to the filterBox Filter 4000 | up to 4000 litres of water with filter foam fine and coarse + Filtra-sub