A second option other than the deflector / fountain look is to position the end of the pipe just under the water surface. I could mount it so that it is angled and facing up towards the surface of the water. This would cause an updwelling of water and would assist in water circulation. I would think this would accomplish the water/air interface because all of the water from the well would end up on the surface of the pond as it was discharged from the end of the pipe (not sure if that makes sense).