hi bro, your way works is becuase once the pump is off the water flow back to the sump which will make the water level reach the pump working minimum lvl. correct me if i'm wrong. provided john is make a higher sump.
Hi jonh you may want to try by fitting with at check valve bellow the pipe which is in the sump water. This will trap water in the pipe so that when power supply came back it will have enought water to do the primeing.It should work.