Good advice. In my case, my sump is big enough to handle all the water that my tank will return through the pump when it is shut off. But I also have a check valve in the line that only allows the water to drop to the overflow boxes. That way, the water in the display tank only drops about 1" with pumps shut off. BUT, if the check valve fails, the sump can still take all the water...

I shut off my return pump for feedings, but leave the closed loop running. This tends to circulate the food to all the critters. Reefkeeper 2 is adjusted for a 10 minute delay. By then, every morsel is history...