My skimmate does not smell either or is that dark. That said, the brown sludge that collects on the neck is more than I have seen on any other skimmer. Also, for the first time, I have been using 100 micron filter bags on all my returns to the sump (2X returns and 1X skimmer return) and all three bags are pretty nasty looking after a week and they do smell when they come out of the water. And I do feed the fish to the point of gluttany!