Not Skimming much

I've had my 55g mixed reef set up for about 6 or 7 months now, and things are great. I am concenred about the skimmer though.  Recently it hasn't been skimming much at all and I'm worried that the DOCs are building up.  It's a SeaClone 100 and it has worked great so far, but I can't figure out why the sudden drop.  I cleaned the whole thing a couple of weeks ago because it had lots of little sponges growing in it.  Here are some pics. Any help would be great!



this has been running for about a week, and normally the cup would be full by now.


It's not so bad in this picture, but i've seen lots of foam collect up here.


just this last week I noticed a persistent protein film on the water surface.  Normally I have no film at all since I have my pumps pointed up for surface agitation.









Edited by Deluxe247 - April 12 2010 at 10:22am

Nothing is blocking the airline or anything.  I think I just have a hard time finding the sweet spot on the venturi valve for the perfect mix of water and air.  I'll keep trying to adjust.

Thanks guys. I checked out some mods on RC and someone mentioned doing a pin-wheel mod on the maxi-jet 1200 to get better micro-bubbles.  I may try it with some old bio balls, but I was thinking about just replacing the maxi-jet with a pin-wheel pump like a reef octopus 2000.  my concern is that the reef-octopus is rated for 500 gph while the MJ 1200 is only 295.  Would 500 gph be too much for the SC100 skimmer or would it actually be better?