I had the same problem w/ mine, so after much frustration, I ended up picking up a valve to adjust the flow from the pump, I also made sure that the flow on the skimmer (red knob) was adjusted so the bubbles do not go above the bottom of the cup,finally what also helped was the needle point had to be slightly (1/2inch) out of my sump, & from than it was doing what it was supposed to....skim!
We used the 220 and found it a bit difficult to adjust from wet to dry skimming, the adjustments had to extremely slight with the knob on it. Otherwise it would fill up a five gallon bucket in no time. We used it for our cycle time and felt it worked well for our tank not stocked (120g). We have since upgraded the skimmer because I wanted to keep a small aresenal of fish but all in all for the money I don't think it was a bad skimmer at all. Just a bit more difficult than others to adjust(but we knew that from reading the many skimmer threads here and on the net)
There are a couple of threads on here where some members did mods to them, which we would have done if we didn't get the new skimmer. Good luck with it.
Do a search on over at RC, they was a huge thread about this skimmer. Also the few things that you need to check are:
1. The pump is only a few inches below the water line.
2. Do the gate valve mode, this will help controlling the water level
3. Give it time to break in.