For aquariums up to 400 liters. Benefits of CO2 fertilization: CO2 partially dissolves in water as carbonic acid. With CO2, you can adjust the pH level (acidity) of the aquarium water to optimal, natural values for fish and plants. Aquarium fish, in particular, thrive in slightly acidic water, which positively affects their very sensitive skin. Essential trace elements for plants and fish are more readily available. Unsightly lime deposits on plant leaves (biogenic decalcification) are avoided. Healthy plant growth means no algae. In aquariums with well-growing aquatic plants, pesky algae have virtually no chance. Algae-promoting nutrients like phosphates and nitrates are immediately absorbed by the plants. However, if CO2 is lacking, plant growth stagnates. Excess nutrients are no longer consumed quickly enough, giving algae a chance, as they can thrive with minimal CO2 amounts. Therefore, good planting and regular CO2 fertilization are among the most important preventive measures against algae. Complete set consisting of: convenient Dennerle disposable supply bottle 500 g, CO2 pressure reducer Evolution Quantum, CO2 addition device Flipper, CO2 special backflow preventer, CO2 hose Softflex, 2 m, CO2 special indicator.