So my 180 has been insanely loud ever since I set it up. The dual returns empty into filter socks and the water flow falls about 6" before it hits the water. Also, my skimmer drain sits about 1" above the water and makes a lot of splashing noise. So I made two mods tonight. I cut 2 pieces of 1" pipe about 6" long and I put them into the filter socks and pushed them up into the bulkheads on my filter sock holders. Much, much quieter! So the skimmer drain posed a more involved problem, I can't introduce back pressure or the skimmer will overflow. So I cut a 2" piece of 2" drain pipe and then took a drill and drilled 4 holes around the edge to diffuse the water as it flowed through it. I then inserted it in the end of my skimmer drain. Much better!
Only thing left is a gurgle sound from the 2" drain pipe itself from the skimmer and the hum of my pumps. The volume difference is huge.