bilge pump question

[macojoe]

I just got my 2 new pumps in today, no hose as of yet, but was thinking about same thing? But my thought would be that the water being pumped out would come back thur the pump thats not pumping at that time?? Which means ihave to put two new thur hulls in and my boat has 3 already for two old pumps that i am leaving in, one small 500 in front and one small 700 in rear. The two new ones are 1100 auto's, i will use the 2 smaller ones for manual when needed, auto's for when on the mooring.
But after getting these 2 Rule pumps and installing them they kept coming on every few min? Instructions say they come on every 2 min for like 2 seconds looking for water, if no water they shut off if there get water they stay on till its gone? Thats ok i guess but i don't want the battery going dead looking for water? This is so there isno float switch to get stuck, they say??