[Side view of skimmer and refugium
[img]http://www.bigleaforchids.com/reef/sump/sump25s.JPG[/img] alt="">] said:
[Peter, go ahead and remove the foam pad from your skimmer and you'll get a much more silent operation from it. You don't need it, and it is a nitrate maker.
Then again, I know your clams need some nitrates, but I can see the water pouring off and I know that can't be silent. You might try washing it out thoroughly.
I linked your pictures to the matching thread on RC, so others could see it in action.]