Subsurface Aeration Can Improve the Health of Aquatic and Plant Life in Ponds

During summer all contained water bodies, like ponds, suffer from low oxygen levels at lower levels. Why does this happen?

Why Install Subsurface Aeration?

Low oxygen at lower levels happens because the water at the surface gets warmed by the sun and develops a warm water layer on it. This layer keeps growing throughout the summer and sits on top of cooler water creating a boundary called the Thermocline. This causes stratification which prevents the mixing of cold and warm water. This results in the bottom level of water getting lower and lower in oxygen levels as it does not get its chance to mix with the surface of the pond that is rich in oxygen because it is exposed to the atmosphere. Subsurface aeration breaks up the thermocline and permits the circulation of warm and cold water.

The Result of Low Oxygen Levels

Water that has no oxygen will become stagnant and can grow algae that many people are allergic to. Stagnant water also allows the breeding of mosquitoes. Phytoplankton can grow excessively and consume all the oxygen.  Low oxygen levels can lead to fish being killed, which will die when oxygen levels are below 1mg per litre. Plantlife will also suffer under these conditions. 

Subsurface Aeration

This becomes necessary in ponds that have a depth of more than 5 or 6 feet. It can be achieved by using an air compressor on the shore connected to an air diffuser by a submersible airline and which is installed at the bottom of the pond. The air pumped in through the diffuser breaks up the air into small bubbles as it passes through rubber or membrane. 

These bubbles rise from the bottom of the pond to the surface where they mix with the already oxygen rich surface water. This also results in the thermocline being disturbed and allowing the free circulation between the warm and cold layers of water. Their effect is not obvious at the surface, unlike in surface aerators. All mixing happens below the surface of the water making these aerators non-invasive. These subsurface aerators also consume less power.

Factors to be Considered for Subsurface Aerators

The circulation created by any aeration system that is installed below the surface is directly related to the depth of the pond, and you will require different types of systems for shallow and deep ponds. The area of ponds can also determine the number of aerators that will be required. Shape can also influence this selection of aerators.

Image from: otterbine.com

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