In a flood drain system where using a timer for your pump, do you need to aerate separately from the pump so you have oxygen in the fish tank during the "drain" period of your cycle?
My six media beds drain into standpipes, pencil thin streams of water, so the water is well aerated while draining. Still, I use a separate pump for aeration in the tank, to supplement during hot weather and as a redundant source of aeration, should the other pump fail. I wouldn't want to lose fish that I've fed for several months. It is generally held that you can't have too much aeration.