Electrical Conductivity of a Hydroponic Nutrient Solution

7/30/2019 Electrical Conductivity of a Hydroponic Nutrient Solution

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Conductivity is the measurement of the capacity that a material has to lead thloaded ionic particles and therefore they have this abil ity. Whichever is greater thethese ions dissolved in the water is greater. Therefore the measurement of the ela direct relationship with the amount of dissociated solid materials that there

Conductimeters are apparatuses used to measure conductivity. Basically thisplates of a special material (platinum, titanium, nickel covered with gold, graphite,measurement scale. Applied a tension between the conductimeter's plates, it me

With the values of the appl ied voltage and the electrical intensity of the current thataccording to their previous calibration, the conductivity of the tried sample.

There are many types of conductimeters and the conductivity values are relatedreally measures a specific conductivity which is the product of the really measursame one. This constant is a relationship between the surface of the plates and the

Conductivity measurements also is dependent on the sample's temperatureconductimeters have automatic devices to compensate temperature changes. Othe

important for their consideration in hydroponics.

!.the electricalconductivity

measurement on anutrient solution

has a directrelationship with

the amount ofdissociated solid

materials thatthere are

dissolved in it.

Different ways for talking about Electric

The well known Ohm's law tell us that when somebody apply a tension between two points of a conductor a circuladirectly proportional to the applied voltage and inversely proportional to the conductor's resistance.Thus:

I = E/Rwhere

I is the current intensity measured in AmperesE potential tension in Volts,

and R the resistance in Ohms.

Purest water doesn't carry electrical current. However, when water contains anelectrolyte dissolved in i t becomes a conductor where the resistance is proportionalto the distance between electrodes and inversely proportional to the area of them.Thus:

R = r.L/Awhere

ris the specific resistvity measured in Ohm/cmL is the distance between electrodes in cm,and A is the area of these in cm2.

The inverse of specific resistivity is the specific conductivity (k). This is: k=1/randtherefore its uni t of measurement stays defined as Ohm-1.cm-1.

Hystoricaly being Ohm-1 the inverse of resistance unit it was cal led mho, the original word written other way around. Thus,the specific conductiv

In order to simplify, during the last decades of the XX century, the mho unit was changed to be denominated Siemens assigning the capital lconductivity unit stay as S/cm.

For many this page's readers everything described here can seem a great tangle. But this explanation, complex for most people, has been neceinstruments using in different form all these units and submultiples of them. There are a lot of confusion between the users. As corolario the follo

when electrical conductivity of a nutritious solution is measured, the specific conductivity of that dissolution is determined.

the unit of measurement of this specific conductivity is the Siemens/cm or S/cm.

equivalences between units and the forms in which frequently they are expressed are the following ones:

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Electrical Conducti


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To practical effects the four emphasized units in the red l ine above are those that hydroponics fans can find in their apparatuses. Most commonby million). The relationship with this last one is empirical and approximate since there are certain interferences on the ions loads transport of ththis one but i t is unnecessary to the practical effects. In order to express equivalence in parts per millon of disolved solids, diverse authors agreebeing 0.640 sufficiently accepted, by each 1 EC. Cal ibration apparatus in ppm use these empirical factors.

CF unit spread mainly in Australia and Nueva Zelanda is 100 times greater that the EC uni t.

On the other hand, the unit dS/m often can be seen mainly in papers from USA researchers.

Ec's for different plants

Values of conductivity most acceptable ranges for many different plants have been compiled. To build this chart the author used all bibliograpbeing complete. In order to have a wider and precise information on EC acceptable values, we will appreciate from the readers complement

please use the e-mail [email protected]

To didactical effects plants were separated in four groups according to their food requirements. However, nutritive solution concentrations arehigh. Since there are several superpositions at the range's extremes, this division is only relati


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Higher EC values?

Recently this page author's has been surprised after a very interesting statement of atechnicaly inquestionable New Zealand hydroponist. In order to provide that

information to others, the principal concepts are copied below." The secret to obtaini

is to grow them at a ve

Another well known hydroponist from Australia, is supporting the above information as follo


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Electrical Conductivity of a Hydroponic Nutrient Solution

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