It sounds to me like you got a lotta junk that needs to come out of the water LOL
, your particular kind of foam must be very sticky.
(edited) oh also if you have additives or anything weird or oils or whatever like water conditioner in the water, it makes skimmers go nuts. (Edited)
Maybe try taking that lid off and just fabricate a little temporary gutter and drain system so when the cup gets full it overflows into the gutter and runs down a hose into a bucket or 1gal milkjug.
You gould do this with hotglue and pieces of acrylic (or similiar plastic) and a couple feet of vinyl tubing. Heck you could probably ductape something together until the excess skimmate problem subsides. Then put the cap back on.
Just my 2cents hope it helps a little, I am combatting microbubbles with my remora right now.