Anybody tried a gravity feed set-up for circulation?

[Tarolisol]

Im not sure if this was what dalphinus was saying but, heres what i tihnk. How about the upstairs tank overflow runsinto another holding tank somewhere above your basment tank. And in that holding tank there is a float valve light in a toilet tank so when the upstaris overflow fill the middle holding tank to a certain point it opens the valve and lets the water surge into the basment tank.