[cleanable and reusable] Balles of organic filters for fish tanks can be cleaned and reusable. They are delivered with a net bag for cleaning filters every 3 months. [Sure and durable] This aquarium filter balls is made of plastic, without danger, non -toxic, durable, will not change quality some water. This can help create a pleasant living environment for aquatic creatures. [clean water] The filtering media of the aquarium can help clean your water naturally and cultivate beneficial bacteria with these polypropylene balls. > [Practical and effective] with multiple pores, water changes direction to prolong the culture time of nitrifying bacteria. [largely application] These aquarium filter balls are suitable for fresh water and ‘Seawater. They can be used with other accessories, applicable to different types of aquariums and aquariums.