Potted plant watering system. (Involves water pumps.)

Using Arduino Project Guidance
78

The definitive bit of code:

This kind of proves my problem and the WHY is beyond me.

There are 6 LEDs in total. 1 - 5 for the loop and a "loop running" LED.

#define LED 8

void setup()
{
    int i;
    for (i=0;i<5;i++)
    {
        pinMode(LED+i,OUTPUT);
        digitalWrite(LED+i,LOW);
    }
    pinMode(1,OUTPUT);
    digitalWrite(1,LOW);
}
void loop()
{
    while(1)
    {
        int i;
        //digitalWrite(1,HIGH);            //  With this line active, LED 5 doesn't glow.
        for (i=0;i<5;i++)
        {
            digitalWrite(LED+i,HIGH);
            delay(500);
            digitalWrite(LED+i+1,HIGH);
            digitalWrite(LED+i,LOW);
            delay(500);
        }
    }
}

I don't know if I can put it any better than the above sketch.

Oh, and please don't pick the "there is not a # 5 LED defined in the loop".
There are 5 leds in the loop. 1 to 4 glow. 5 doesn't with the line un-commented.
But with the line commented out, # 5 does glow.