Betta Air Curtains create a decorative curtain of fine bubbles and can be shaped as required around rocks etc. The air curtain improves aeration of aquarium water circulation of water and helps prevent build-up of toxins. To install, connect to standard 4/6mm silicone or plastic air line from a suitable air pump. An air pump (not included) with an output of approximately 4.5 litres per minute is recommended for the best effect.