A skimmer in a backyard pond serves two purposes. First, it acts as the lowest point in the system that determines the level of the pond. The side opening in the skimmer is where water flows, drops into the pump area and is pumped up to the top of the pond for the return flow.

Second, skimmers are part of the filtration system. They contain a mesh bag through which the water flows on its way down to the pump. The bag catches large objects such as leaves and the occasional fish. Between the bag and the pump are layers of foam filter material which begins the process of removing some of the smaller particles. This removes them from the water and protects the impellers on the pump too.

The skimmer at the right is designed to sit in the center of a pond. The water flows into the top opening and down to the bottom where a flexible tube is attached that leads to the pump unit. 

The unit above is made to be placed at the edge of the pond. Water flows into the unit and through a netting to catch larger items such as leaves. The pump is placed in the bottom of the unit and flexible pipes will take the water up to the top end of the pond for recirculation.

• The skimmer is sunk into the ground at the edge of the pond. The height of the opening on the side determines the depth of the pond. There are two holes in the back of the skimmer box. The lower one is where an overflow outlet is connected so that the water level does not rise too far in the pond. The higher opening is for the pipe that returns the water to the biofilter/water fall unit. 

• The mesh in the skimmer collects large particles such as leaves or other floating materials.