Log-in or register your account to remove these ads! Its free and an e-mail isn't required.

From The Aquarium Wiki

milligram per litre (mg/l)

Often used to describe the concentration of chemicals dissolved in water.

This measurement of unit is mainly used in the EU and internationally.

mg/litre = ppm, equals ml/l. So 4mg/l equals 4ppm or 4ml/l