The eheim aquacompact 40 is a compact and innovative external filter it is a combination of an internal and an external filter for small open aquariumsr the flow is easily adjusted using the regulating dial on top of the canisterr the unit has an integral prefilter to collect mechanical debris before it reaches the pump which protects it and prolongs the cleaning intervals a nozzle and spraybar are both included for natural surface movementr r suitable for aquariums of 20 40 litresr outpu