California Man: I noticed that when ever I install a new skimmer or when I clean my skimmer, there is a lot of condensation it at first. When it starts working (producing skimmate) it goes away and is replaced by foam. It was true with my Seaclone, my Aqua C EV-150, and now, with my ER CS 6-2+. It is probably due to the water evaporating from the bottom of the skimmer rising through the open neck (with no foam) into the cup. It stops when the neck is filled with thick foam. Right or wrong, my 2 cents.