Qanvee Bio Sponge Filter is a multi-filtration equipment for shrimp or fish tank It can be used with a combination of mechanical chemical and biological filtration which creates clean and clear water for the aquarium 1 Connect to air pump produce a lot of bubbles and increase the oxygen content 2 Filtration cotton provides vast surface area cultivate high density nitrifying bacteria playing the role of biological filtration 3 The filter containers design can hold more filter media and provide greater adhesion area for nitrifying bacteria with better biological effect Size: Qanvee Bio Sponge Filter comes with 2 models: 1 QS100A - can hold 100g filter media recommended for tank under 15gal 2 QS200A - can hold 200g filter media recommended for tank over 15gal Please note filter media is not included!