What size stone do you have, where did you put the inline connection, and how's it oriented? I decided to put mine downstream of my plate chiller. I used a union on the back of it. I'm pretty sure I put in the 2 micron stone. I prefer to keep my tee fitting horizontal because I have a thrumometer next and it lays better on my wire rack. Sometimes some wort leaks through the stone as I am not running O2 the whole time chilling. I put a QD on the O2 line, and with the union and a QD for the main line to the fermenter the inline O2 is removable. I also put a small 1/4 plastic valve ($0.99) upstream of the O2 QD because I didn't like the brass valve on the O2 container. The threads are backwards and it's hard to see the arrows on the brass valve. Those red O2 bottles are $10 a piece and I lost one (operator error).
I can tilt mine off the horizontal and that helps when the O2 isn't running. I like to keep mine removable for easier cleaning is why I have it setup this way but there might be better configurations.