The pump is most definately the noise culprit. I use a mag7 on my Berlin skimmer. I added a venturi valve on mine which helped a lot. I think it cost $15 or so. These skimmer need some adjustment from time to time but they do work. I have been running mine for about 3 yrs.
*180 gal Display, 100 gal basement sump, 33 gal refugium, 3x250 MH, 2x160 VHO actinics, zoos, some softies, LPS & lots of acros and other SPS.
*100 gal prop tank plumbed into main system w/ 2x96 PC lights and 1x150 MH,