Aeration: More Than Just Pumping Air
An increasing appreciation for our natural resources and awareness of the environment around us has increased the focus on natural water systems that exist in our landscape. Whether it is a farm pond, a recreational fishing lake, or a retention pond that treats storm water, all of these systems benefit from management. Ponds exhibit a natural aging process involving the incorporation of nutrients from various sources, plant growth, and organic sludge accumulation. These natural processes are slowly but definitely turning our ponds back into land over time. Ponds and lakes receive a constant barrage of nutrients from the watershed areas that serve to fill them. A wide range of naturally occurring and not so naturally occurring material is challenging our aquatic environments on a daily basis.
Grass clippings Fertilizer from landscapes Pet waste Pesticides and Herbicides Storm water including eroded soil and debris Eroded topsoil Petroleum residues Leaf litter from trees and shrubs Waterfowl waste Farm animal runoff Aquatic vegetation seasonal thatch
When these materials enter the aquatic environment they increase nutrient levels. One of the first responses is by aquatic vegetation, including algae and rooted plants which take up nutrients during growth. Simultaneously, bacteria begin to decompose the material as well. The aquatic plants, unless physically removed will eventually return these nutrients to the water in the form of dead algal cells or seasonal plant thatch. This can result in rapid filling from the edges of the pond with sludge from degradation of seasonal thatch. Depending on the algae population and species, organic sludge from algae can form an ever increasing sludge layer on the bottom. Disregarding flushing that may occur, bacterial degradation of organic material into gases that can exit the aquatic environment represent the only permanent method to remove these nutrients once they have entered.
Reversal of this filling process after it has been allowed to advance is possible but many options are expensive, disruptive to the pond and the adjacent landscape (chemical treatment, draining, or dredging), and these may involve regulatory or permitting processes.
Ponds are an asset to real estate that needs to be preserved and maintained. New construction is costly and it makes good sense not to defer maintenance and allow the deterioration of your investment.
Aeration is an effective, simple, and environmentally friendly technique for the maintenance and rejuvenation of ponds.
Aeration helps water exchange gasses with the air. One positive result is increased levels of dissolved oxygen. Maintaining healthy levels of dissolved oxygen in your pond aids in the breakdown of decaying vegetation and other sources of nutrients that enter your pond. This breakdown of the bottom silt is carried out by bacteria at the water/soil interface and continues to proceed a few centimeters deep in the pond mud. This decomposition can be carried out in two ways, aerobically (with oxygen) or anaerobically (without oxygen). The decomposition is slower and less complete in anaerobic verses aerobic conditions. Aerobic decomposition requires a continuous supply of oxygen and proceeds more rapidly with higher oxygen levels. With aerobic decomposition the primary end product is carbon dioxide which can physically exit the water into the atmosphere. Organic sludge in anaerobic conditions does not degrade as rapidly, and the end products are incompletely digested, foul-smelling organic compounds. In summary, the more decomposition we can facilitate through the addition of oxygen, the less nutrients there will be available for additional sludge development, algae blooms, and excess aquatic plant growth.
Necessary oxygen levels from natural sources are unpredictable. Your pond’s environment receives life-supporting oxygen from the atmosphere at the surface where the air and water contact each other, as well as from the photosynthesis of algae and plants below the water surface. These processes are both affected by weather: available wind energy (wave action) and sunlight. Weather is unpredictable and that can create stagnant water and low oxygen levels. When there is no sunlight, there is no photosynthesis to create oxygen. In stagnant water, there is no physical energy to help the water and air exchange gases and water forms well defined layers of different temperatures. Warm summer water holds less dissolved oxygen, and the demand for it increases during this time. Poor environmental conditions in the pond for fish and other organisms are the result. The aging process continues with the erratic unpredictable supply of oxygen.
The use of an aeration system will help nature keep up with the demand for dissolved oxygen and prolong the life of your pond. Aeration dramatically improves environmental conditions in your pond and helps keep good water quality predictable. Aeration accomplishes this in several manners:
· Oxygen levels increase and distribute throughout the pond stabilizing the system against future challenges.
· Harmful gases are expelled. These are gases that are byproducts of organic degradation. Carbon dioxide, methane, and some nitrogenous gases as well. If allowed to increase in concentration, further organic breakdown is halted.
· Organic sludge accumulation is reduced or reversed. Bacteria are stimulated and consume a greater amount of sludge and the volume is physically reduced.
· Circulation that accompanies most forms of aeration serve to reduce stagnation, distribute nutrients in a more diluted fashion which eliminates problem pockets. The temperature layers are disrupted bringing a large portion of the pond volume in contact with the atmosphere. This also facilitates distribution throughout the pond if chemical treatment is necessary
· Fish growth and health are improved. Fish can inhabit new areas previously restricted by low oxygen. Fish are less stressed with higher oxygen levels and that means heavier feeding, more vigor, and less disease with better survivability of young fish which results in more sustainable populations and balance. Fish are also protected from the ultimate disaster: a fish kill from insufficient oxygen.
· Odors from anaerobic breakdown of organics are reduced or eliminated.
· Overproduction of algae is reduced. Nutrients are simply less available and concentrated because they are being expelled, diluted, or bound. Many are being expelled from the pond through gas exchange with the atmosphere. Phosphorus, which is a key nutrient in algae production, is additionally bound by pond mud that has higher oxygen levels.
· Think of aeration as an insurance policy to protect you invest of time as well as money.
There are many types of aeration and depending on the type that you choose to employ, you may also receive other benefits: daytime and nighttime display, surface tension disruption that leaves the surface looking clear and fresh, a pleasant sound of falling water that can screen noise from adjacent highways or lawn maintenance equipment. As public opinion and regulations push further away from the use of chemicals, aeration will provide the ability to treat you water with reduced or even eliminated use of these chemicals. You will see a savings in chemical cost, labor costs for the application of the chemicals, and the labor cost in the physical removal of algae mats.
Aeration systems need proper maintenance to keep them operating at their optimum capacity. This includes changing the compressor filters externally and internally, keeping the inside of compressor cabinets clean of debris, and cleaning the diffusers as needed. Depending on the property that your pond resides on, your aeration system may need this maintenance once a year or quarterly. Windblown sand or an abundance of dirt, coupled with hard water determines the frequency of maintenance. Cason & Associates provides this maintenance service to our aeration clients at regularly scheduled time periods to keep their systems running at peak efficiency.