Plant nutrient concentration

Electrical conductivity (EC) can be used to compare the relative overall nutrient concentrations of different brands of otherwise similar types of nutrients.

This is done by measuring the EC value of the nutrient when diluted 100 fold (10ml into 1,000ml) with distilled water. To do this, add the following volumes* to 1,000ml (1.05 Qrt) of distilled water:

1-parts: 10ml of nutrient.

2-parts: 5ml of part ‘A’ + 5ml of part ‘B’.

3-parts: Collect a total of 10ml from all 3 bottles in accordance with the ratio of parts used to achieve a given formulation type. For example, 10ml of ‘bloom’ formulation may be comprised of 4ml part ‘A’ + 4ml part ‘B’ + 2ml part ‘C’.

Typically, the strongest 2 & 3-parts yield between 2.4 and 3.0mS. Comparable, “slurry” type 1-part’s can far exceed 3.0mS - see Graph 7.40.

*For accuracy, use a finely graded pipette (or equivalent device) for measuring out the nutrient.

Note: This method does contain a degree of error because the conductivity of different mineral salts varies (See “Effect of salt type”).