Hi Mechatrons
NOTE : For TESTING purpose, i checked the code with LED blink. Instead of water delivery , i used onboard LED. (no problem with onboard LED).
So for testing, you changed pin 8 to be pin 13 for the onboard LED on the Arduino? And this worked ok on external power?
Did you change the timer values? If not, you must have waited for 12 hours from start to see the LED change?
And can you confirm which type of Arduino you are using.
Regards
Ray