vertex omega 150 skimmer

I purchased a Vertex omega 150 two weeks ago, it is now running on my 72g reef. Prior to use I ran it in a vinegar bath for a few hours then rinsed with RODI. Then followed all the break in instructions from vertex. It seems I can not get it to dry skim. and the foam head will not stay consistent. The skimmer is sitting in 7" of water, and the level stays consistent. Sometime it over flows randomly to. Any help would be great! thanks guys!