• Lynne Melvin

What Is Fine-Bubble Water Aeration?


Fine Bubble Water Aeration is the number one treatment for ponds, storm drainage systems, farm dugouts, lagoons, and lakes. Fine bubble aeration subsurface aeration is air introduced in the form of very small bubbles originating at the diffuser plate on the bottom of the pond or lake. The bubble size of the typical coarse bubble diffusers is much larger than the fine bubble diffusers, thus, having a lower oxygen transfer efficiency (OTE). Fine bubble water aeration efficiently increases dissolved oxygen levels in the body of water and mixes the water column from top to bottom, dissolving the thermocline.

Dissolved oxygen is important in many ways. Fish and other aquatic species require dissolved oxygen to survive and thrive. Fish Kills result from low oxygen levels in a pond or lake. Without dissolved oxygen, the pond or lake is in an anoxic state. Dissolved oxygen also facilitates beneficial aerobic bacteria to consume excess nutrients in the water and helps them to work faster & more efficiently in the presence of dissolved oxygen. As the beneficial bacteria remove the extra nutrients, it leaves the algae with no nutrients to utilize for growth, thus promoting clean, clear algae-free water.

What is Subsurface Water Aeration?

Subsurface aeration is located at the bottom of a pond, lake, or wastewater lagoon. With the proper diffuser design, the water is entrained from the mud water interface, which brings dissolved oxygen into contact with muck at the bottom of the waterbody. Dissolved oxygen will increase the speed and efficiency in breaking down the muck/sludge at the bottom of the pond, lake or lagoon. Subsurface aeration releases the built-up gases from the bottom of the pond, which reduces the smelly stagnant water. The bottom of a lake or pond is typically anaerobic due to the anoxic conditions from the thermocline in the water.

Subsurface diffused aeration draws the dissolved oxygen to the very bottom of the pond or lake. When dissolved oxygen reaches the bottom, it promotes the digestion of muck on the bottom, thus reducing the aquatic weeds that grow in this muck.

Why is Subsurface Water Aeration Important?

Thermal Stratification – the temperature change layer between the bottom of the water body and the top. When you are swimming, it feels quite cold on the bottom, and the top is warm; this is thermal stratification. This stratification essentially separates the water resulting in less mixing. Therefore, the bottom layer tends to become anoxic (low dissolved oxygen). The build-up of gasses on the bottom can not penetrate the thermocline to exit the water column, nor can the dissolved oxygen from the top penetrate to reach the bottom.

Why does this matter?

Thermocline creates an anaerobic state where the anaerobic bacteria (not requiring dissolved oxygen) slowly break down organics, release nutrients into the water, and produce gas such as hydrogen sulfide (rotten egg smell).

Aerobic bacteria is a beneficial bacteria that require dissolved oxygen to thrive and will be less abundant on the bottom when a thermocline is present. Subsurface aeration has the potential (depending on plate design) to entrain water from the mud/water interface. The water from the bottom of the water column is dragged to the top and released as the fine-bubbles rise.

The fine bubbles in the water interact and exchange dissolved oxygen as they rise and surface. With subsurface fine bubble aeration, dissolved oxygen circulates down the bottom, and the thermal stratification no longer exists. The dissolved oxygen should be present from top to bottom. This is why the type of diffuser plate is critical and is truly what sets the aeration system apart from others on the market. The Airmax ProAir4 diffuser plate has four tubes with very fine openings in which the air comes out 360 degrees. This design has been proven using dye tests to circulate the dissolved oxygen down the mud.

Increasing dissolved oxygen in the water column, delivered to the bottom of the pond, helps to activate the aerobic bacteria. Aerobic bacteria work very quickly to consume organics and nutrients in the water and release them as a gas, Carbon dioxide.

With the reduction of nutrients and muck (sludge) in the bottom of the pond, the water is healthier, cleaner, and clearer. Algae and nuisance aquatic weeds need nutrients to flourish. When aeration is added to the water, thus increasing the dissolved oxygen, the aerobic bacteria reduce the available nutrients and muck bed for the weeds and algae to grow, thus starving it.

Advantages Of Fine Bubble Subsurface Aeration vs Coarse Bubble Aeration:

  1. Exhibit Higher OTES

  2. Exhibit Higher Aeration Efficiencies (Mass Oxygen Transferred Per Unit Power Per Unit Time)

  3. Satisfies Higher Oxygen Demands

  4. Lower Cost To Operate

  5. Modular In Design