CF (conductivity factor) is a unit of electrical conductivity common in Australian, New Zealand and some UK hydroponic literature and meters. It is EC scaled by ten to avoid decimals: 1 CF = 0.1 mS/cm = 100 µS/cm. So a solution of 1.6 mS/cm is CF 16.
In practice
CF is a straight multiplication, with no conversion-factor ambiguity, unlike ppm. If a nutrient chart from Australia says "CF 12–16 in veg", that is EC 1.2–1.6 mS/cm. Some older Australian charts quote even higher flower values (CF 20–25); treat those as upper limits, since controlled cannabis trials do not show yield gains from pushing nutrient concentration hard.
When sharing numbers on GenetixBay, use mS/cm so everyone reads the same scale.
Units and formula
Don't confuse with
- Conversion factor: the multiplier that turns EC into ppm (0.5 or 0.7); despite similar words, it is a different thing from CF.
- ppm: a calculated estimate that depends on meter scale.
EC (electrical conductivity) measures how well a solution conducts electricity, a proxy for total dissolved salts; growers read it in mS/cm to gauge nutrient strength.mS/cm (millisiemens per centimetre) is the standard unit of EC for nutrient solutions; 1 mS/cm equals 1 dS/m and 1,000 µS/cm.µS/cm (microsiemens per centimetre) is a unit of EC one thousandth of mS/cm, used mostly for low-conductivity water such as RO and rainwater.ppm500 is the TDS scale that converts EC to ppm with a factor of 0.5 (based on sodium chloride), so 1.0 mS/cm reads 500 ppm.ppm700 is the TDS scale that converts EC to ppm with a factor of 0.7 (the 442 natural-water standard), so 1.0 mS/cm reads 700 ppm.The conversion factor is the multiplier a TDS meter applies to EC to report ppm, commonly 0.5, 0.64 or 0.7; it is why ppm readings differ between meters.
