I have a bioskim 600 made by US Aquariums. The cool thing about it is that it is an all-in-one system, biological, mechanical and protein skimmer in one. This is great because you only have one box sitting on the back of the tank. It works very well and the air does enter the skimmer with the water. The whole thing only cost me $150 at my lfs and I have never lost a fish or been overwhelmed by algea.