I am trying to increase the flow back to the pond from the filter. I\nincreased the size by 1/4" and am concidering adding another return line to\nthe pond. The filter (tetra PF3) is a cannister above the pond. Currently\nthe line discharges about 8-10" below the waterline. Does having the\ndischarge line below the watersurface slow down the water flow?