Friday, August 6, 2010

The Facts About Aeration

Adequate aeration is arguably one of the most cost-effective management tools available to pond and lake owners to improve the quality of their aquatic resource. Although aeration is particularly important in smaller ponds (less then 3 surface acres in size), medium sized ponds and even lakes can also see dramatic improvements in water quality and water body health as a result of aeration. It is important not only to understand how aeration systems work, but also the difference between the types of aeration systems as well as the chemical and physical need needs of your water body. The most common benefits of aeration include: Increased dissolved oxygen concentrationPrevention of fish stress and mortalityRemoval of carbon dioxide and ammoniaMinimization of algae growthIncreased vertical and horizontal water circulationElimination of odorsImproved water qualityIncreased surface disturbance, thereby discouraging the successful development of mosquito larvae Many pond owners mistakenly consider aerators and fountains to be the same thing. This is not the case. There are distinct and significant differences between surface aerators and surface fountains. The three most common aeration methods for ponds and lakes are briefly described below.

Surface Aerators:

surgace aerators

True surface aerators function by moving a large volume of water (800 – 1300 gpm.) a maximum of 3-4 feet into the air, thereby increasing gas transfer within the pond, inducing circulation and improving water quality. As a result of the massive amount of water being pumped into the air and splashing back down onto the water surface, a wave action radiates outward from the unit towards the pond or lake perimeter. Surface aerators are extremely effective in ponds which are less than 10 feet deep. The size, shape and depth of your water body will influence the size and quantity of surface aerators you need. A surface aeration system may be as simple as one unit or may involve several units strategically located around the water body. View our Aerator Models & Online Pricing

Surface Fountains

surface fountains

The primary objective of surface fountains is to create an aesthetically pleasing water feature. Similar to surface aerators, surface fountains function by pumping water into the air, thereby increasing gas transfer within the pond and improving water quality. However, a surface fountain pumps the water much higher (typically 4-15 feet), subsequently, the volume of water is significantly decreased (typically less than 250 gpm.) and, as a result, the aeration efficiency and gas transfer rates are dramatically reduced. The size and quantity of surface fountains is more often driven by aesthetics than the size, shape and depth of your water body. Often surface fountains are combined with one or more surface aerators to provide a complex water display feature while achieving superior water quality improvements. View our Fountain Models & Online Pricing
Subsurface Aeration System As you might expect, subsurface aeration systems are entirely different from surface aerators or fountains. Rather than pumping water into the air to increase gas transfer and induce circulation, subsurface aeration systems pump air into the water. Systems of “synergistic airlift diffusers” are placed on or near the bottom of the water body. Compressed air is pumped through underwater airlines to the diffusers, bubbles out of the diffusers, and rises through the water column to the surface. As the air rises, the bubbles expand, entrain the surrounding water molecules and “pump” them towards the surface, producing a gentle boiling of water and bubbles at the surface. These systems are extremely effective in destratifying a water body. In fact, the greater the depth the more efficient the system. Subsurface aeration systems are most effective in ponds with a depth greater than 12 feet or in lakes, and are not a cost effective option for smaller water bodies. Not all aeration systems are created equal. One must closely examine actual pumping rate, oxygen transfer rate and amperage draw of the motor before making a determination as to which system to purchase. For over 50 years, the Rowledge Pond Fish Hatchery has utilized aeration units from a wide variety of manufacturers, and we have even made a few of our own. We have found the PowerHouse surface aerators and surface fountains are the most durable, efficient and effective surface aeration systems on the market. We use PowerHouse surface aerators exclusively in our hatchery facility, and are proud to be their Northeast distributor. Rowledge Pond Aquaculture can assess your pond or lake and design, build and install an aeration system for you which meets both your property management objectives as well as the ecological needs of the pond.

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