Just add citric acid, baking soda, water into the bottle, can produce carbon dioxide. The plant metabolic rate can be increased quickly, create the best growing conditions for fishes. It is the best choice of making CO2 equipment at home. Features: Professional CO2 generator system with stainless steel bottle, better than simple plastic bottle generators. It is more reliable, steady, durable and efficient. Safety valve will open automatically when the pressure over the safe pressure. Bubble counter with check valve: Flow-rate of CO2 gas indication device and prevent water flow back into the regulator. Solenoid valve: To control the on and off of CO2 generator system using with a timer(not included). Come with a bubble diffuser, refine the bubbles and make it easy to dissolve in water and be absorbed by plants. Inject to your aquarium with CO2 quickly and easily. Large amount of CO2 may cause fish dead. It is recommended to reduce the CO2 volume at the beginning, 1 or 2 bubbles per second. One time's reaction can last for 3 to 4 weeks using. Note: Excessive or double addition of raw materials and water is prohibited. Invert the bottle and disassembly are prohibited. Specifications: Main material: Stainless steel Main color: Silver Voltage: AC 100V-240V input; DC 12V output 3 size optional: 1L: Height: 22.5cm; diameter: 10cm; thickness: 0.12cm; 2L: Height: 47cm; diameter: 10cm; thickness: 0.12cm; 5L: Height: 47cm; diameter: 13cm; thickness: 0.15cm; Package size: 1L: 34*12*12cm / 13.4*4.7*4.7in 2L: 48*12*12cm / 18.9*4.7*4.7in 5L: 50*14.5*14.5cm / 19.7*5.7*5.7in Package weight: 1L: 1000g / 35.3oz 2L: 1705g / 60.2oz 5L: 2705g / 95.5oz Package List: 1* Stainless steel bottle 1* SolenoidValve(1L Not included) 1* Bubble diffuser 1* Pressure reducing valve 1* Bubble counter with check valve 1* Filter 1* 1.5m tube 2* Suction cup 1* Manual