Electric Conductivity

 int  R1= 1000;
 int  EC_Read = A0;
 int  ECPower = A1;
 int Temp_pin = A5;
 float Temp_C;
 float Temp_F;
 float Temp1_Value = 0;
 float Temp_Coef = 0.019;

 ////////Calibration/////////////
 float Calibration_PPM = 1080;    //Cehck with solution of knowm PPM//
 float K = 1.77;                  //Value of K will be specific for your probe//
 float PPM_Con = 0.5;

 //////////////////////////////////
 float CalibrationEC = (Calibration_PPM * 2)/1000;
 float Temperature; 
 float EC;
 float EC_at_25;
 int  ppm;
 float A_to_D = 0;
 float Vin = 5;
 float Vdrop = 0;
 float R_Water;
 float Value=0;
 ///////////////////////////////////
 
 
 
void setup() 
{
  // put your setup code here, to run once:
    Serial.begin(9600);
    pinMode (EC_Read, INPUT);
    pinMode (ECPower, OUTPUT);

    /////////////////////////////////
    
    //Calibrate (); // After calibration make it comment by adding two //
    

}

void loop() {
  // put your main code here, to run repeatedly:

   GetEC();
   delay (1000);
   
}

//////////////////////////////////////
void GetEC()
{
  int val;
  double Temp;
  val = analogRead(Temp_pin);
  Temp = log(((10240000/val)-10000));
  Temp = 1 / (0.001129148 + (0.000234125 + (0.0000000876741 * Temp * Temp )) * Temp);
  Temp_C = Temp - 273.15;
  Temp_F = (Temp_C * 9.0)/5.0 + 32.0;
  Temp1_Value = Temp_C;
  Temperature = Temp_C;
  digitalWrite(ECPower, HIGH);
  A_to_D = analogRead(EC_Read);
  A_to_D = analogRead(EC_Read);
  digitalWrite(ECPower, LOW);
  Vdrop = (Vin*A_to_D) / 1024.0;
  R_Water = (Vdrop*R1) / (Vin-Vdrop);
  EC = 1000 / (R_Water*K);
  EC_at_25 = EC / (1+ Temp_Coef*(Temperature-25.0));
  ppm= (EC_at_25)*(PPM_Con*1000);
  Serial.print(" EC: ");
  Serial.print(EC_at_25);
  Serial.print(" milliSiemens(mS/Cm)  ");
  Serial.print(ppm);
  Serial.print(" ppm  ");
  Serial.print(Temperature);
  Serial.println(" *C ");
}

///////////////////////////////////////

void Calibrate ()
{
Serial.println("Calibration routine started");
float Temperature_end=0;
float Temperature_begin=0;
int val;
double Temp;
val= analogRead(Temp_pin);
Temp = log(((10240000/val) - 10000));
Temp = 1 / (0.001129148 + (0.000234125 + (0.0000000876741 * Temp * Temp ))* Temp);
Temp_C = Temp - 273.15;
Temp_F = (Temp_C * 9.0)/ 5.0 + 32.0;
Temp1_Value = Temp_C;
Temperature_begin=Temp_C;
Value = 0;
int i=1;
while(i<=10){
digitalWrite(ECPower,HIGH);
A_to_D= analogRead(EC_Read);
A_to_D= analogRead(EC_Read);
digitalWrite(ECPower,LOW);
Value=Value+A_to_D;
i++;
delay(6000);
};
A_to_D=(Value/10);
val=analogRead(Temp_pin);
Temp = log(((10240000/val) - 10000));
Temp = 1 / (0.001129148 + (0.000234125 + (0.0000000876741 * Temp * Temp))* Temp);
Temp_C = Temp - 273.15;
Temp_F = (Temp_C * 9.0)/ 5.0 + 32.0;
Temp1_Value = Temp_C;
Temperature_end=Temp_C;
EC =CalibrationEC*(1+(Temp_Coef*(Temperature_end-25.0)));
Vdrop= (((Vin)*(A_to_D))/1024.0);
R_Water=(Vdrop*R1)/(Vin-Vdrop);
float K_cal= 1000/(R_Water*EC);
Serial.print("Replace K in line 11 of code with K = ");
Serial.println(K_cal);
Serial.print("Temperature difference start to end were = ");
Temp_C=Temperature_end-Temperature_begin;
Serial.print(Temp_C);
Serial.print("*C");
Serial.print("Temperature difference start to end must be smaller than 0.15*C");
Serial.println("");
Calibrate ();
}