Well, I was against adding another overflow and decided that to add a closed loop, I'ld have no choice. However, with a little more research and somebody else's successful attempt, I turned my overflow into a durso by making a lid that allows me to adjust the air/water going to the sump... hence less air obstruction to mix with and rise against the water going down. I was able to add another 720 gph pump to an already 900 gph going through the display(not including the 4x200gph powerheads on a wavemaker). Also, I just changed out my pc's and halides(same ol' reliable XM's) and replaced my carbon. Finally, I did a couple of small relocations in the aquascape.