[sasquatch]

check the water pump for problems. A faulty or underpowered pump
will not drive the air-induction injector properly, which will lead to low
levels of foam production.
B. Check the water level inside the skimmer's main chamber. An
incorrect water level will prevent proper foam production. Adjust the
exit valve so that the interior water level is near the top of the main
chamber (fig. 5).
C. AquaC protein skimmers feature an intense air flow-thru rate, which
means that they are highly influenced by oils, fats, and other chemicals
dissolved in the aquarium water or air source. You will notice a drastic,
temporary reduction of foam production after fish feedings or other
events which introduce chemicals into the water. Foam production
should resume within several minutes to a few hours, depending on
the nature of the chemical disturbance. This should not be any cause
for concern since your high performance skimmer will rapidly make up
for any time lost due to the disturbance.
D. Wipe away any salt creep that might have accumulated around the
base of the foam tower. There is a very thin air gap between the foam
tower and skimmer box – if this air gap becomes clogged with salt
build-up the skimmer will stop foaming. Salt can be removed by
dribbling hot water through the gap and scraping it away with a piece
of wire or plastic.

This is from the manual, what pump are you using, where is it installed, any pics?? Steve