What happens if your not home and the power goes out for a few mins then comes back on. Will your "thing" keep it's siphon and start draining when the pump kicks on or will the pump only turn on and pump all the water from your sump into the tank and then onto the floor?.........First I plug up the overflow exit with a pvc cap, fill the fish tank to the brim so the water is at least 1/2" to 3/4" over the overflow return in the tank, then using the vacuum I suck the water from the vertical vent until the overflow is primed. Once I have prime, I fill the sump over 1/2 full and start the pump. This set up is very cost effective and works great. Frank.