A few facts about ec, ppm, cF, and pH

1.      Electro-conductivity (EC) or Conductivity factor (cF) can be expressed as either millisiemens (ms), cF or parts per million (PPM) 1 mS = 10cF =
700ppm

2.      The pH and electro~conductivity values specified here are given as a broad range. It should be noted that specific plant requirements will vary according to regional climatic conditions, and from season to season within that region.

3.      As a general rule, plants will have a higher nutrient requirement during cooler months, and a lower requirement In the hottest months.  Therefore, a stronger nutrient solution should be maintained during winter, With a weaker solution during summer when plants take up and transpire more water than nutrients.

4.      KNOW YOUR CROP.     Plant EC or cF may vary according to the stage of growth. For example, cucumber prefer cF 20 when establishing, and cF 25 after the first harvest. Between and 7 weeks after first harvest, the optimum cF is 17.

5.      For easy growing reference, plants that share broad groupings of low, medium or high can be grown together using the same nutrient electro- conductivity, providing middle ground cF is adopted.

6.      The nutrient solution should be discarded at regular intervals. Should there be a requirement to flush the growing bed, the system should be flushed with fresh nutrients (run-to-waste) rather than water to avoid starving or stressing the plant.

Following are links to charts for pH/PPM/cF for different plants frequently grown in hydroponics: