My Skimmer won't foam up

[Jaws]

I have similar problems with my Euro Reef. I used to have to pour hot water into the airline tubing once every two weeks or so. My frustration is that once the airline tubing blocks up then the skimmer starts to overflow. Now, even after taking the pump apart and chipping away some salt crip with a knife, I have to use hot water every three days. Only on one pump though. I haven't done a good vinegar cleaning in a few months so maybe I'll try that.