I use a seaclone 100, you need to have the black air adjustment knob on the air line.
1.) put it back on
2.) open the valve wide open, you will see that the J line will have air in the top of it
3.) slowly close the air adjustment knob, each time waiting about 30-45 seconds for the adjustment to take affect. Keep closing the valve until the air bubble at the top of the J line vanishes
4.) Wait 30-45 seconds, the back-off the valve (open it) just slightly
Now leave it, it is now adjusted. You should see some skimmate over the next few days, it may take a few days for it to break in. If you don't get any skimmate after a week, then either you don't have anything to skim (which I doubt) or the unit is defective in some way.
People do not speak highly on this skimmer, but I can state that it works great for me.