Your fish load isn't all that high for that skimmer and the Clarisea is removing solids before they become dissolved which the skimmer would use to generate the foam head. between the relatively light load for the skimmer size and the clarisea, there isn't going to all that much dissolved organics for that skimmer to keep a good foam head. I would suggest running the skimmer at 10" and maybe bump the pump to 32 watts if closing the wedge pipe more than 1/2 way is needed to get the line where bubbles turn to foam is up to the base of the neck if not a little bit higher. Cleaning the pump might help but it's hard to say as I don't know how clean your pump is to begin with.
Unfortinatly it wont make much of a difference. When opening the wedge i get this:
10" deep
1/2 open
32w
Any suggestions?