Fountains or Aerators – How to Decide What’s Ideal for Your Lake’s Health

Part 1 – Lake depth less than 10 ft.

Pond and lake aerators, whether surface or subsurface, greatly improve the water quality of any aquatic environment. A properly sized and well-placed aeration system helps maintain oxygen saturation within the water column, which is a necessity for water quality management. Maintaining oxygen saturation in a pond or lake not only benefits the micro-fauna, but it also gives Mother Nature a boost in reducing the amount of excess nutrients in the water column via organic digestion and oxidation. By reducing the nutrient load, there is less “food” for aquatic vegetation to consume, thus less undesirable algae growth and a much happier pond owner!

Choosing an aeration system seems like an arduous decision, however it’s much easier when you understand the features and benefits of each system along with the dynamics of the pond or lake to be aerated. With most ponds and lakes being man-made storm water basins, the challenge becomes even more important for us to become better stewards of the environment and think long term with our aeration solutions.

There are three basic types of pond and lake aerators: surface spray aerators, air diffused systems, and horizontal mixers. Additionally, fountains are often a desired choice or option and have their benefits as well. Each type has unique applications and efficiencies which can be utilized in several ways to achieve maximum benefit. For the remainder of this article, we fill focus on the best aeration solutions for lakes with a depth less than 10ft.

Surface Spray Aerators

Surface spray aerators are often categorized as fountains. True, a floating surface spray aerator may have a “fountain” like pattern, but the characteristic design between an aerator and fountain are inherently different. A surface spray aerator’s main function is to provide oxygen to water, and its second importance is to provide increased circulation and mixing via the high flow or pumping rate. A surface spray aerator is “aerobic exercise”; it’s like putting a pond on a treadmill—the more you work the water out the healthier the pond becomes.

Fountains 

A fountain is made by pressurizing water and channeling it through various chambers or nozzles to provide a decorative pattern, thus reducing the flow rate and its ability to be used to aerate water. However, any time you break the surface tension of the water (such as the splashing of a raindrop or the wave-like action created by the splashing) you will achieve oxygen transfer, therefore a fountain will have some aeration qualities.  However, a fountain’s Achilles’ heel is its low pumping rate, which renders it less efficient in terms of beneficial aeration for lakes and ponds.

Subsurface Aeration

Subsurface diffused aerators, sometimes called “bubblers”, utilize a shore mounted compressor that pumps air to diffuser manifolds on the lake bottom. The micro bubbles that are emitted float to the surface and entrain or “push” the water from the bottom to the surface to be aerated. The bubbles rise at about one foot per second, and it’s not until the bubbles break at the surface and the water spreads out through the atmosphere that oxygen diffusion or transfer happens. This type of bottom-up system is most effective and efficient in waters 10’ or deeper. The deeper depths allow for more contact time and a greater amount of water to be lifted to the surface for aeration.

Our expectation for this introduction is to help you better understand the types of aerators you have to choose from for managing water quality, and how they best fit your long-term goals for your pond or lake. In the next issue, Part 2, we will focus on how to properly size an aerator based on the depth, size, shape and history of the pond or lake. In the meantime, if you would like to learn more about aerators and fountains, or need assistance determining the depth(s) of your pond or lake, please reach out to us at any time at 678-445-0077.