Many will bash the SeaClone (it is no where near top of the line) but don't worry too much. They DO work and pretty well as far as I'm concerned, you just have to find the right setting and adjust quite often.
Keep in mind that it takes some "break in" time. If you've only had it a few days don't worry. Also, if your tank is fairly new there might not be much gunk for it to pull out.
Don't open the valve all the way. If you do, you will actually lose water flow into the skimmer. I open mine as far as I can so that I get max bubbles but there is no air trapped in the tube coming out of the tank.
You shouldn't have any or many bubbles coming into your tank. I have heard this can be a problem with SeaClones, however I have not had that problem. Again, just adjust the valve to where the issue stops.