Laurel Hill Trout Farm, Inc.

Aeration is probably one of the best things a pond owner can do to help maintain a healthy pond.  Besides providing increased oxygen levels for your fish, aeration also helps circulate the water in your pond, vent off harmful gases and helps provide extra oxygen for beneficial bacteria to help decompose all the waste material which accumulates at the bottom of your pond, such as leaves, dead algae, and fish waste.  Without oxygen, bacteria cannot break down these wastes, and they will just keep adding to the muck at the bottom of your pond, adding more fuel for future algae and weed growth.  Without oxygen, you would not be able to survive; the same is true for the fish and bacteria living at the bottom of your pond.

In most ponds without aeration, the pond will stratify (separate into layers) during the summer months.  The warmer water then rises to the top and the colder water stays at the bottom.  While the top layer is continuously recharged with oxygen, the oxygen is eventually used up in the bottom layer.  Once the oxygen is used up in the bottom layer, it creates a dead zone where fish and beneficial bacteria no longer can thrive. Please see diagrams below.

Types of Aeration:

Surface Aeration:  Includes fountains and other splash type aerators.  In surface aeration, the fountain or aerator floats on the surface of the water.  Surface aerators work by throwing the water into the air and breaking the water into small droplets,  allowing for oxygen to enter the water and harmful gases to be vented.  Because the aerator sits on the surface of the water, in deeper ponds surface aeration may not circulate the water all the way to the bottom.  Surface aeration is often best suited in applications where a visual effect, such as a fountain is desired, or in shallower ponds, typically under 10’. 

Diffused Aeration:  In diffused aeration systems, air is pumped from a shore side compressor through tubing to a diffuser or diffusers located on the bottom of the pond.  The diffuser then breaks the air into small bubbles which then float to the surface, circulating water as the bubbles rise to the top.  Diffused aeration systems are very good at circulating the entire water column in the pond.  Also, because the air is introduced at the bottom of the pond, oxygen levels are increased at the pond bottom where it normally is the lowest.  Diffused aeration systems are great for deep ponds or where minimal surface disturbance is advantageous.