I run this skimmer and it's great!
Mine is in 9" of water and i run it with the air input silencer at the wide open setting. Also I adjust mine so the water/bubble interface is right where the cone body ends and joins the collection cup. If its adjusted right you can remove the cup and the bubbles stay in the body. At this setting mine makes a nice dry foam that fills the cup in 3-4 days.
Nasty smelling stuff to I must say!
Don't forget to clean the inside of the neck when you empty the cup of the effectiveness goes way down.
Hope that helps.
