I'm building a tank from scratch but this inquiry has mostly to do with the back pressure of the return pump if the power goes out. Years ago if I cut the power on my return the water would instantly reverse flow into the sump or onto the floor<depending on water level in the tank where it meets the return plumbing> . Was this a fault of my return pump or is this a normal phenomenon? How has technology changed within the past 10 years? If nothing has changed, how would I remedy this issue the CORRECT way? Thanks in advance!