The skimmer head is floating on the water surface, an air pocket is ensuring it is best possible position.
Under the function of the water pump, a thin water-screen can be sucked by the skimmer,the little motes can go into the pond filter through the skimmer, but the big dunghills, like branches, leafs and other floaters will be hold up in the filter basket.
The large volume filter basket can extend the maintenance period.