Eheim Diffuser 12/16mm to

Optimal fresh air supply for aquarium water
The diffuser from EHEIM supplies fresh air from outside and thus enriches the aquarium water with oxygen. The supply of oxygen is particularly recommended for weakly planted aquariums or those with a high fish population. It is also popular for cold and sea water tanks or for keeping fish that are correspondingly oxygen-loving. Where a cover limits the air space above the water surface, additional air should be added.