Home FAQ

 

This measurement is derived from a measure of the Electrical Conductivity ( E.C. ) of a solution. E.C. can be measured in millieSiemens per cm2 and for normal plant growth hydroponic nutrient solutions are in the range 0.5 to 4.5 mS/cm2. The cF is the E.C. value multiplied by 10. ( E.C. 1.0 is equivalent to cF of 10 )

The cF is one measure of the concentration of the nutrient salts and any contaminates in solution. Plants tend to fall into three groups requiring a high, medium and low cF...

This measurement is derived from a measure of the Electrical Conductivity ( E.C. ) of a solution. E.C. can be measured in millieSiemens per cm2 and for normal plant growth hydroponic nutrient solutions are in the range 0.5 to 4.5 mS/cm2. The cF is the E.C. value multiplied by 10. ( E.C. 1.0 is equivalent to cF of 10 )

The cF is one measure of the concentration of the nutrient salts and any contaminates in solution. Plants tend to fall into three groups requiring a high, medium and low cF.

Wilting, leaf scorch, bolting and other abnormalities will be experienced when you grow plants in cF levels outside their prefered range.

Because most of the materials in water used in hydroponics are salts the mineral content of a nutrient solution is sometimes referred to as the Total Dissolved Solids ( TDS) in the nutrient solution.

Sometimes you will find reference to PPM ( parts per million ) but the convention in hydroponics is to use either E.C. or cF as the units to measure the strength of a nutrient solution.

As a guide only:

Leafy greens, lettuce, beans and most herbs require a low cF ( 7 to 15 in winter and 15 to 18 in summer.

Cucumbers, melons, many ornamentals and some cabbage-related crops like medium cF 16-18 in summer and 18-22 in winter.

Tomatoes, peppers and eggplants prefer a stronger cF 25 - 36 in summer and 36 to 50 in winter.

For more detailed information on optimum cF levels for different plants read Hydroponic Gardening by Steven Carruthers pages 12 & 13 ( ISBN 0 85091 557 0 )