What is TDS  and EC ?

TDS :–Dissolved solids” refer to any minerals, salts, metals, cations or anions dissolved in waterTotal dissolved solids (TDS) comprise inorganic salts (principally calcium, magnesium, potassium, sodium, bicarbonates, chlorides, and sulfates) and some small amounts of organic matter that are dissolved in water. TDS is measured in ppm (parts per million) or in mg/l.

EC :–THE ELECTRICAL CONDUCTIVITY OF WATER. The electrical conductivity  of  water estimates the total amount of solids dissolved in water .

To get an EC value, multiply the ppm reading by 2 and divide by 1000.

Thus, if your EC is 1:

1*1000/2= 500 ppm.

And if your ppm is 500:

500*2/1000= 1 EC

 Is it better to use an EC or a TDS meter?

If you have plant nutrient recommendations in EC units, an EC meter is convenient. If your plant nutrient recommendations are in ppm values, a sodium chloride TDS calibration is easier to use.

 Why is conductivity of the nutrient important?

Conductivity is a measure of the strength of the nutrient solution. The higher the conductivity, the more dissolved solids there are in the solution. Delicate plants, cuttings, and seedlings can experience fertilizer burn if the conductivity is too high. Once the plants begin growing, they need a stronger nutrient solution, so conductivity must be increased by adding concentrated nutrient. Some plants prefer a milder nutrient strength, while others grow better and produce better quality fruit with a higher concentration.

How does conductivity affect plant growth?

Conductivity is really a measure of the nutrients in the solution. Low conductivity implies a low nutrient concentration, which usually results in nutritional deficiencies and slow growth rates of your plants. One can look at the situation, as a higher conductivity is more food for your plants. However, be careful of very high levels as this can burn and or kill the plant.