Tetra CO2 Plus is a liquid CO2 aquarium plant fertilizer. CO2 is an essential nutrient for a healthy and lush plant growth. Tetra CO2 Plus adds carbon to the water in a form ready accessible for plants.this is how Tetra CO2 Plus works:+ Biological release of CO2 up to one week+ Aquatic plants develop stronger and healthier+ Easy to use without any additional appliances+ Vigorous plant growth is the best algae prevention+ Dosage: Add 2.5ml per 20 litres of aquarium water every week+ In case of high planting apply twice a week.