Skimmer not collecting very much at all

[Fish?]

So I got this smaller skimmer that came with my tank 4-5 months ago, and you cant actually adjust the air it takes in and you can only adjust the height it's at in the water, I adjusted it in the beginning to where it looked like it worked, and I would always top off the tank. The thing never collected much anyway, but as of now I cleaned it like two weeks ago and there is like less than one fifth of an inch in the collection cup, after the two times I cleaned it did barley collected anything. So what should I do?

 

[KrisReef]

Lower the adjustment and you will collect more. Feed more and you will collect more.

edit: post a picture and you will get better replies!