I bought an aqua life 115 skimmer. The first week that I had it, i thought I made a bad buy. The water in the collection cup was clear, and when I adjusted the knob, there weren't sufficient bubbles. I do 5 gal pwc to my 16 gal tank every week so people were telling me that there probably wasnt enough waste for the skimmer to work. So i decided to pulled it out and put it into storage. A month later, I gave it another chance before selling it. It was the same for the first couple of days. Then one morning, I woke up to some yellow-brown muck in the collection cup.
I have a innovative marine 16 tank, and I placed the skimmer in the main area instead of the refugium section in the back. It's an eyesore, but it does the job. I empty a yellowish brown cup every 2 days and I see solid waste in there as well. I have to rinse the cup every week because there build up of brown slime. If I move it into the back part of my tank, I wonder if I'll have the same result.