after having receive questions via PM I bring some clarification:
this is a downdraft skimmer. This is not a needle wheel.
Water is propelled through the inlet pipe and proceeded through BioBall to produce bubbles (so there's no venturi pump). Unlike Venturi skimmer, the water level is maintained at about 2 "-6" because of the amount of air passing through the skimmer. A very dark, fragrant foam is produced quickly and in large quantities and with this design.
Water enters "a", the injection system, where water is restricted in a 1 / 4 propelled in" b ", the BioBall, which break the air into water to bubble in the "c". Then, the bubbles come out of "d", then up, the bubbles are deflected by a deflector "e" up to the "f" that sends the skimmer is mounted the foam "g", and skim very thick and smelly accumulates in the cup "h".
We made a modification in the tube "b" by adding a Becket injector. therefore even more bubbles!