[Delphinus]

I think for any brand-new skimmer you have to wait for it to break in a little, which usually takes a few days. If you're still not getting foam after a week then something is wrong. I don't want to alarm you but that is a complaint I've sometimes heard about the the in-sump models. You may have to play around with things. I have the hang-on model myself. It doesn't take very long to start pulling thigs out, but then again it is like a four-year old skimmer (I have my own little mini-reef of biodiversity in the skimmer itself), so it's well past any break-in period.

I use a mag 7 as my pump driving the skimmer.

Good luck, and keep us posted.