Any tips and advice would help. My skimmer pulls out light green skimmate and looking to see what I can do to have pull black dark skimmate. It's currently sitting in sump approx 8 in deep. I just dont feel it's working to it's full potential. I have 2 tangs blua and yellow 2 clowns. Total of 7 fish. Sometimes it looks like skimmer foam level drops a little and not much foam falls into collection cup. Any advice would be great. Thx