Question
I have a 15 year old system that shows that the power is on yet no zones work.   I did notice that a kiddie pool had been left over one of the heads.

Answer
Hey Mike, I hope this helps. The pool would have no effect on the system not working. I would first check your controller, and make sure it is sending out current to the valves. And also check and make sure your main water valve is turned on to the system. Let me know what you find out. Good luck and have a great day.