You can put on automatic watering and you won't have to worry about closing the valve.
The same to fill the tank, you automate it so that the pump starts and opens the solenoid at a low level and stops the pump and closes the solenoid with a full tank.
The valve you have to put it, for possible failure of the pump, to isolate it and not empty the tank. It is not necessary to close said valve at the end of irrigation.
hello ennio The valve should not close normally, just buy it thinking of a common tank where if it is usually put but then I thought that for some reason, someone could close it and maybe the pump would operate with this closed, but now that I think about it it is unlikely that Someone will touch her.