I have an odd issue with my well, it is set at 90' and so far I have replaced the pump, tank and pessure switch. Now here is the issue the tank will read 50psi then the sprinklers turn on and the pressure drops to 0psi. At this point if I shut the sprinkler valve the system starts to build pressure very slowly. If I then cycle the circuit breaker for the pump it then "snaps" the pipes and starts to build pressure at a normal rate. At this point, I can re-open the sprinkler valve and the system seems to run fine until it is left to sit for a lenght of time (over night for example). The only thing I can think of is maybe a stuck foot valve. Any advice would be greatly appreciated.