Model: ACB-300; jetting volume: 17 L/min; recommended air pump power: > 7 W; standard ID airline tubing: 3/16 inch. Ideal for fish tanks, aquariums, DWC systems or small koi ponds. 2 Bubbles Effects: Produce a cascade of fine bubbles under less air input and medium bubbles under strong input. Both form a rectangle bubble wall to increase oxygen level in your aquarium. Stable in Water: Each bar measures 12" L x 1.5" W and weighs 4 oz. Come with an extra suction cup clip which keeps it lying steadily without floating in the water. Reliable Material: Compressed with sand and wrapped with a plastic base, it causes no effect to the health of your aquatics. Help keep fish or roots growing healthily. Easy to Use: Soak the stone completely in water for 1 hour before use. Clean it regularly with a brush as it gets clogged after weeks or months of usage. MODEL: AWB-300. Jetting Volume: 15 L/min, PUMP POWER NEEDED >7W and pressure> 0.025 MPa, such as whissper AP150.