The JBL ProAqua Test CO2 Direct is designed for quick and accurate determination of the carbon dioxide content in aquarium water.+ Contains 2 reagents with colour comparison field.+ Easy test to perform, where the droplet number is counted until the colour stays stable.+ Determines the exact CO2 content, even if the pH value is reduced by adding acid.+ refill pack availableCarbon dioxide (CO2) is the most important plant nutrient. Aquarium water usually has values between 2 and 4 mg/l if no carbon dioxide is added. However, a CO2 concentration between 15 and 30 mg/l is recommended, with 20 - 25 mg/l having proven to be optimum levels. This level is not harmful to fish whilst at the same time promoting luxuriant plant growth. Therefore, gradually adjust your CO2 fertilisation unit until this level is attained. The amount of CO2 which needs to be added to your CO2 fertilisation unit to achieve this value depends on various factors. These factors include water agitation and the intensity