We are attaching LED's to the front of the tank. The code that will make the LED's flash is;

int led0 = 8;

int led1 = 9;

int led2 = 10;

int led3 = 11;

int led4 = 12;

int led5 = 13;

void setup() {

pinMode(led0, OUTPUT) ;

pinMode(led1, OUTPUT) ;

pinMode(led2, OUTPUT) ;

pinMode(led3, OUTPUT) ;

pinMode(led4, OUTPUT) ;

pinMode(led5, OUTPUT) ;

}

void loop()  {

digitalWrite(led0, HIGH) ;

delay(50) ;

digitalWrite(led0, LOW) ;

delay(100) ;

digitalWrite(led1, HIGH) ;

delay(50) ;

digitalWrite(led1, LOW) ;

delay(100) ;

digitalWrite(led2, HIGH) ;

delay(50) ;

digitalWrite(led2, LOW) ;

delay(100) ;

digitalWrite(led3, HIGH) ;

delay(50) ;

digitalWrite(led3, LOW) ;

delay(100) ;

digitalWrite(led4, HIGH) ;

delay(50) ;

digitalWrite(led4, LOW) ;

delay(100) ;

digitalWrite(led5, HIGH) ;

delay(50) ;

digitalWrite(led5, LOW) ;

delay(100) ;

digitalWrite(led4, HIGH) ;

delay(50) ;

digitalWrite(led4, LOW) ;

delay(100) ;

digitalWrite(led3, HIGH) ;

delay(50) ;

digitalWrite(led3, LOW) ;

delay(100) ;

digitalWrite(led2, HIGH) ;

delay(50) ;

digitalWrite(led2, LOW) ;

delay(100) ;

digitalWrite(led1, HIGH) ;

delay(50) ;

digitalWrite(led1, LOW) ;

delay(100) ;

}