It comes with a cheesy plastic air valve at the end of the airhose that goes into the powerhead. I popped it off and put a brass valve on instead for better control. The intake tube i shortened is the U-tube going from the powerhead over the tank to the bottom of the skimmer, i cut it so the intake of the powerhead would be as close to the water suface ass possible without drawing air. The airstone sits at the bottom of the skimmer in the centre, just drill ahole in the collector cup cap and run a line through it with a stone right doen the middle of the cylinder to the bottom. All these mod ideas came from this board and have worked well for me. Good luck!