What Size of a Surface Aerator Do I Need?

Types of Systems and Ponds

• Surface aerators are used in commercial fish production, storm water ponds and in backyard ornamental ponds. Each of these ponds requires a different type of surface aerator. Commercial ponds depend on industrial-type surface aerators. These large aerators are capable of turning over and aerating acres of surface water. The types used are paddle aerators that are powered by motors. The motors turn large paddles that effectively agitate water and allow oxygen bubbles to penetrate deep water. Other types are electric pump sprayer aerators and electric propeller aspiration pumps. Storm water ponds that require aeration use diffuser systems. These systems pump air throughout the pond using powered pumps that push air from the bottom of the pond to the top. Similar systems are used in backyard ponds, but small backyard ponds can also use much smaller fountains and bubblers.

Depth

• Shallow ponds are at less risk of depleted oxygen than are ponds that are more than 8 feet deep. Deep ponds exhibit higher levels of stratification. This means that temperature differences between the pond's surface and the pond's bottom are greater than temperature differences in shallow ponds. The greater the temperature difference, the less likely that water will flow and mix evenly throughout the pool. Instead, water becomes stratified, or layered, with cool water at the bottom and warm water at the top. In these situations, corrective measures include the use of large surface aerators capable of moving massive quantities of water.

Pond Shape and Environmental Conditions

• Ponds can take the form of large, open water reflective pools, but they can also feature canals and bottlenecks. Oddly shaped pools may require more diffusers or a number of strategically placed surface aerators. The aerators do not have to be bigger, but they must be numerous and well placed. Some ponds have portions sited in shade. Shaded areas are more prone to cooler temperatures, which helps improve aeration during hot months. Bright, sunny areas may have a greater propensity to foster algae and other plant growth that can, at times, limit air circulation.

Considerations

• Healthy ponds contain at least 5 milligrams of oxygen per liter of pond water. Levels can be tested using equipment from commercially available testing kits. Monitor oxygen levels and choose an aerator that can keep oxygen levels within a healthy range. Aerators can be judged by the amount of oxygen they produce per hour. This is measured in pounds of oxygen per hour. Commercial pond aerators supply between 2 and 5 pounds of oxygen per hour. Smaller diffuser systems pump oxygen throughout the pond. A one-horsepower pump can provide adequate aeration for one surface acre of pond. Shallow, small ponds can rely on bubblers and fountains to provide adequate air circulation.