Sample Arduino C program to fade and LED slowly on and off and control the delay time of ramp up, on, ramp down and off.

Arduino LED fader

/* Based on the Arduino fader example 
   Dan McCreary
   Nov. 2013 */
int ledPin = 11;    // LED connected from digital pin 11 to ground
int maxb = 155; // max brightness 0 to 255
int inc = 1;  // step increment value: typical values are from 1 to 10 
int slope = 20;  // delay at each step in milliseconds - combine with inc to change speed transition
int delayOn = 1000;  // how long to stay at max brightness in milliseconds
int delayOff = 2000;  // how long to stay off in milliseconds
 
 
void setup()  { 
  // nothing happens in setup 
} 
 
void loop()  { 
 
  // fade in loop
  for(int fadeValue = 0 ; fadeValue <= maxb; fadeValue +=inc) { 
    // sets the new value as we make the LED brighter (range from 0 to 255):
    analogWrite(ledPin, fadeValue);         
    // wait see the dimming effect    
    delay(slope);                            
  } ;
  
  // how long to stay at full brightness
  delay(delayOn);
 
  // fade out loop
  for(int fadeValue = maxb ; fadeValue >= 0; fadeValue -=inc) { 
    // sets the new value as we dim down
    analogWrite(ledPin, fadeValue);         
    // wait a bit  
    delay(slope);                            
  };
  
  // how long to stay at the off position
  delay(delayOff);
 
}

Hi there, great program but please could you tell me how to keep the (delay on) for 7 hours?
My dad is using this program for marine fish tank led's but having trouble with timings.please help.
Many thanks.