alright well i currently just bought a protein skimmer for my 14 gallon biocube yesterday, and hooked it up but the only thing im getting is water in the collection cup, no foam!? what is wrong with it!?
If it is set-up properly, it may take a couple of days to break in the skimmer and when that happens you will start to see the black stuff in your collection cup that you want!
But you should have foam right when you hook up your skimmer..so..when you get bubbles, follow the above. Maybe try the directions again?