Because the dissolved fertilizer value of ion (ion) can provide electricity unit has a Mo / (Mho), but the value of the current is very low. The measurement value is measured in mm / / cm (milliMhos / cm).Measurement of the electrical conductivity will make us know only the total value of electrical conductivity of aqueous nutrient .(that is, water and fertilizer are all nutrient vessel put all the nutrients) only, but do not know the value of the ratio of any one nutrient nutrient inside the tank. That may change over time due to the plants used or precipitation.