How to add email notification in blynk

[JemJem]

I’m trying to put notification in my blynk. The concept of my project is that it can monitor the ph reading, tds reading and water level of water using blynk. I can now see the readings of each sensor. Now this time I want to add notification that if for example, the reading of pH sensor is less than the desired value, it will notify me with gmail. I added some code in my sketch but the error is this.

Compilation error: conversion from 'int' to 'const String' is ambiguous

This is the code that I uploaded

// Fill-in information from your Blynk Template here
#define BLYNK_TEMPLATE_ID "TMPL7li3j7BK"
#define BLYNK_DEVICE_NAME "PH TDS and FLOAT sensor"

#define BLYNK_FIRMWARE_VERSION        "0.1.0"

#define BLYNK_PRINT Serial
//#define BLYNK_DEBUG

#define APP_DEBUG

// Uncomment your board, or configure a custom board in Settings.h
#define USE_WROVER_BOARD
//#define USE_TTGO_T7
//#define USE_ESP32C3_DEV_MODULE
//#define USE_ESP32S2_DEV_KIT

#include "BlynkEdgent.h"

BlynkTimer timer; // Announcing the timer

#define PH_Pin 33          //pH meter Analog output to Arduino Analog Input 
unsigned long int avgValue;  //Store the average value of the sensor feedback
float b;
int buf[10],temp;

int fl_Sensor=32;
int fval=0;
int Redled=5;

int f;  // for float value to string converstion
float val; // also works with double. 
char buff2[10];
String valueString = "";
String PH_Val = ""; 

int DSPIN = 14; // Dallas Temperature Sensor
int TDS_Sensor = 34;
float Aref = 2.3;

float ec_Val = 0;
unsigned int tds_value = 0;
float ecCal = 1;

WidgetLED ledglow(V5); // add virtual LED to V5

void float_Data()
{
 fval = digitalRead(fl_Sensor);  
 if (fval == LOW) 
  { 
    digitalWrite(Redled, HIGH);
    ledglow.on();
    Serial.println( "WATER LEVEL - HIGH"); 
  } 
  else 
  { 
    digitalWrite(Redled, LOW);
    ledglow.off();
    Serial.println( "WATER LEVEL - LOW" ); 
  }

  /*
  if(fval = 1)
    {
      Blynk.email("capstonegroup718@gmail.com","Alert","Water Level High!");
      Blynk.logEvent("float_sensor","Water Level High!");
    }  
*/   


}

void TDS_Data()
{
  // double wTemp = TempRead()* 0.0625;  // conversion accuracy is 0.0625 / LSB
  double wTemp= 27;
  float V_level= Aref / 3500.0;
  float rawEc = analogRead(TDS_Sensor) * V_level;  // Raw  data of EC
  float T_Cof = 1.0 + 0.02 * (wTemp - 25.0);  // Temperature Coefficient
  
  ec_Val = (rawEc / T_Cof) * ecCal;// temperature and calibration compensation
  tds_value = (133.42 * pow(ec_Val, 3) - 255.86 * ec_Val * ec_Val + 857.39 * ec_Val) * 0.5; 
  double Far= (((wTemp *9)/5) + 32); // Temp in Far*
  
  Serial.print("TDS:"); Serial.println(tds_value);
  Serial.print("EC:"); Serial.println(ec_Val, 2);
  Serial.print("Temperature (oC):"); Serial.println(wTemp,2);   
  Serial.print("Temperature (oF):"); Serial.println(Far,2);
  Serial.print("");
 
/*
  if(tds_value < 150)
    {
      Blynk.email("capstonegroup718@gmail.com","Alert","Low Nutrients!");
      Blynk.logEvent("nutrient_warning","Low Nutrients!");
    }  
*/ 

  Blynk.virtualWrite(V1, wTemp);
  Blynk.virtualWrite(V2, Far);
  Blynk.virtualWrite(V3, tds_value);
  Blynk.virtualWrite(V4, ec_Val);

}
void PH_Data()
{
  for(int i=0;i<10;i++)       //Get 10 sample value from the sensor for smooth the value
  { 
    buf[i]=analogRead(PH_Pin);
    delay(10);
  }
  for(int i=0;i<9;i++)        //sort the analog from small to large
  {
    for(int j=i+1;j<10;j++)
    {
      if(buf[i]>buf[j])
      {
        temp=buf[i];
        buf[i]=buf[j];
        buf[j]=temp;
      }
    }
  }
  avgValue=0;
  for(int i=2;i<8;i++)                      //take the average value of 6 center sample
  avgValue+=buf[i];
  float phValue=(float)avgValue*3.0/1024/14; //convert the analog into millivolt
  phValue=4.5*phValue;                      //convert the millivolt into pH value
  
  PH_Val =  dtostrf(phValue, 4, 2, buff2);  //4 is mininum width, 6 is precision
  Serial.print(PH_Val);
  valueString = "";
  delay(1000);
  


  Blynk.virtualWrite(V0, PH_Val);

  
  if (PH_Val < 4)
    {
      Blynk.email("capstonegroup718@gmail.com","Alert","PH reading low level!");
      Blynk.logEvent("ph_warning","PH reading low level!");
    }  
}

void setup()
{
  Serial.begin(9600);
  delay(100);
  pinMode(fl_Sensor, INPUT_PULLUP); // Float Sensor
  pinMode(Redled, OUTPUT); // Red LED
  timer.setInterval(1000L, PH_Data); //timer will run every sec 
  timer.setInterval(1000L, TDS_Data); //timer will run every sec 
  timer.setInterval(1000L, float_Data); //timer will run every sec 
  BlynkEdgent.begin();
}

void loop() {
  BlynkEdgent.run();
  timer.run();        // run timer every second
}