WenzoOoOoOoo... not sure what your asking. If power is lost, pump on filter/overflow and return pumps shut off.
I have my bulkhead drain above the Aquaclear pump so there will be no siphoning the tank, and the pump stays primed. If pump on Aqualcear fails, same result.
I don't keep so much water in the sump that the tank will overflow if Aquaclear fails, return pumps will suck air before tank is completely filled.
My original thought was to install the bulkhead through the bottom, but I would have had to insert a standpipe... and didn't want to hear the gurgling.