It’s common knowledge that 1 ppm is the same as 1 mg/ liter or 1 gram of nutrient in 1 million grams of water. The universal method of measuring the strength of a nutrient solution (where any one in any country will be speaking the same language) is Electrical Conductivity (EC) or (CF) which is really EC with the decimal point moved one digit to the left. For example: 0.8 EC = 8 CF. Stating the solution strength in ppms, (which many growers do) can be misleading, as different salts may weigh the same but have different ppms when dissolved in water. The ppm measurement actually came from waste water treatment or TDS (total dissolved solids), where there are several conversion factors where 1 EC equals either 600 ppm, 640 ppm, 700 ppm, or 750 ppm. That is why EC (Electrical Conductivity) is the industry standard.