The one constant in water is change. Water composition in the winter is different from that in the summer. Weather effects the system. For aesthetic and recreational usage everyone expects lake and pond water to be reasonably clear and algae free. This, then, gives us a working definition of a "healthy" system. Man-made systems are inherently subject to nutrient loading and problems. Nature's reaction to excess nutrients is to produce aesthetically undesirable algae or vegetation. We can augment natural bio-degradation of excess nutrients with aeration and circulation combined with environmental controls. Aeration occurs when oxygen is transferred to lake areas where it is lacking: usually in the bottom area (benthic layer where microbial activity occurs). Aerators add beauty to a water feature from the surface, but more importantly they assist in the natural process of nutrient absorption and reduction by promoting aerobic (with oxygen) bacterial activity below. With proper planning and design it is possible to combine aesthetics with function.

Making Aerators/Fountains a Beneficial Focal Point

This 3-horsepower Lily pattered aerator is located on a golf course lake in Boulder City, Nevada. The pattern is 13'(h) x 13' (w/center "stamens") and 5'(h) x 45' (lower "canopy").

In the selection of an Aerator/Fountain unit, first consider the benefit to the body of water. Where a Fountain is essentially purely for aesthetics, a well designed Aerator both improves water quality and provides aesthetics. Dealing with water quality degradation requires a properly sized Aerator based on its rated volume of water (turnover). An undersized unit is not effective, and might as well be a Fountain. Understanding the rate of turnover required for a lake is important…the more, the better. Finally, consider the visual "fit" of the spray pattern as it relates to the location (architecture, setting, etc.). An incorrect discharge pattern can be tantamount to wearing stripped pants with a checkered shirt.

Discharge Patterns, Lighting Effects

This 2-horsepower Trellis patterned fountain is located in Peru, Illinois, and has dimensions of 21'(h) x 32'(d). Facing Page: As part of the High HP series, this 20-horsepower Tiara is located in Chaska, Minnesota and has a pattern of 36'(h) x 140'(w).

The discharge pattern is the effect created by the water being propelled by the Aerator through the discharge nozzle. Construction and engineering contained in this small but very important portion of the unit cannot be overemphasized. Nozzle design is as critical to the reliable operation of the unit as thrust, back pressure and amperage draw. Without the proper engineering of all these components as a system, problems are certain to occur, and difficult to diagnose. When purchasing Aerators look for the size and number of openings in the nozzle. For instance, dramatically better circulation and aeration is achieved with real Aerator nozzles containing sixteen (16) 5/8" holes or twenty-four (24) 1/2" holes, compared to others with 12 to 18 holes of 1/4" to 5/16" in diameter. Flow rates are 3 to 4 times greater with the larger holes. Also, nozzles made with many small holes simply drilled in a plate usually produce fuzzy, indistinct spray patterns whereas the larger, well engineered nozzles produce large, coherent, beautiful, patterns.

Typically there are many spray patterns to choose from, and an evaluation is an artistic one. Determine the general theme of the landscape and architecture surrounding the water feature. Is it in a developed corporate park with tall, modern looking structures? If so, perhaps a large vertical plume will accent the architecture. What about a more natural setting–possibly a low, less obtrusive shape to blend in with the landscaping? How about the addition of lights? Who are the primary beneficiaries of the improvement: park patrons or wildlife? In the right settings, the addition of a lighting package turns a functional piece of equipment into a beautiful nighttime amenity that dramatically enhances location value.

Water Quality Is Not Just Visual

Water health involves controlling pH, oxygen, algae, vegetation and working with natural Ecosystems. Each lake or pond, man made or natural, is a unique, living, breathing ecosystem. It is important to understand all of its components before fixing any single problem. In most man-made lakes, nutrient overloading is the single most critical issue. Large trees overhanging the water and green grassy areas are typical problem sources. Fertilizer and lots of water keep trees filled out and grass growing. Runoff from unnatural levels of nutrients and water are the primary food sources for algae and vegetation growth in lakes and ponds. These problems can be prevented, first, by checking the make up of the fill water. Municipal sources treated with Chloramines that break down to Nitrite exacerbate nutrient problems. pH levels can create hard water, rendering other methods of maintenance ineffective. An excess of waterfowl within the system adds to a water quality problem. In a given year, an average duck can contribute up to nine pounds of Phosphorous and Nitrogen to a water system. This is the equivalent of purchasing a bag of lawn fertilizer and dumping it into the lake and pond.

How Aerators Improve Water Quality

The 5-horsepower two-stage Lily is located in Florida and has a canopy width of 60' and an overall (stamen) height of 18'. The aerator will move 800,000 gallons of water in a 24-hour period.

Aerators can play a major role in correcting low oxygen, water stagnation, and nutrient overload problems. Lake managers note: only after you have dealt with: Landscape Runoff, Erosion Control, Organic Material/Debris, will Aeration provide its full beneficial effects. Then aeration may just be the "jump start" that the lake and pond needs to turn the corner. Let's look at key lake and pond problems and their aeration solutions, understanding that many individual problems listed below and their solutions may be interrelated.

1) Low oxygen: Dissolved Oxygen (D.O.) levels are essential to a healthy system and ideally should be near the point of saturation. It is also a natural occurrence for D.O. levels to drop during the evening hours, as oxygen consumption increases due to plant activity. We tend to forget that a beautiful looking Fountain or Aerator is in operation for more than our own selfish pleasure. Truly, the primary objective is to augment the water body health through oxygen exchange. Even units without lights should be operational in the nighttime hours to ensure optimal water quality.

2) Poor or no circulation: The water in a perfect lake and pond is exchanged on a regular, daily basis, throughout all its locations. Ah, but there is no perfect lake. Aerators play their most important role by adding circulation to areas that lack it. Lake areas such as sheltered fingers and coves, prevailing winds (lack of), flow through (lack of) can create stagnant or "dead" spots where water quality begins to degrade. Aerator placement can improve these locations, acting to boost Nature's process. This is especially important in lakes and ponds that no have little or no flow during the warmest weather.

Water quality solutions that involve manmade re-circulation depend on scale, and are subject to regulations and permits. Water circulation is critical to water quality. Swimming pools without circulation/filtration will not maintain water quality in warmer months using all the pool chemicals in storage. The same is true for a lake and pond. Assess system capacity, then apply the one-time-per-day water turnover rule for optimal circulation. A one-acre, one million-gallon capacity, aeration unit should theoretically "move" one million gallons per day (24 hours).

To insure that the Aerator is actually circulating the entire lake or pond it is vitally important that suction be taken deep in the pond. Even though an Aerator may be pumping an adequate volume, most have shallow intakes and do not create adequate circulation. Most Aerators take suction immediately under the float and so they simply are recirculating the same water. Aerators with standard deep suction naturally provide complete circulation, and can be easily and economically extended to any depth so that circulation can be achieved from the bottom of any pond, even a very deep pond, thus creating the required complete pond circulation.

Lakes are not always uniform in their depth and warmer areas will develop. Circulation, by any means is essential to achieve water temperature de-stratification and water exchange. The simplest means of achieving this goal (aside from actual water exchange) is through the installation of a deep suction Aerator, which can be placed where needed and requires no fixed plumbing or suction pumps. In some applications, more than several may be required to effect the needed water turnover. In shallow areas a "low draft" horizontal pump Aerator, designed and manufactured by Aqua Control, is unique in that it can be located in water areas as shallow as 20", just where circulation is needed the most in warm seasons. Until these new aerators arrived on the scene, the only option for water quality improvement in shallow areas was dredging to increase the water depth.

Deeper water naturally forms a thermocline, an area that separates warmer and cooler water and prevent mixing. Most everyone has experienced this phenomenon when wading into the water at a lake beach and has noted the cooler water at the feet and lower legs. In warm weather a layer of warmer and usually adequately aerated water stays in the surface layer above the thermocline, but below the thermocline the water is cooler and is frequently oxygen deficient. Inadequate sunlight penetrates thus reducing photosynthesis which lowers oxygen produced. The limited available oxygen is consumed during the decomposition of organic matter that is on the bottom. These deeper lakes and ponds that form a thermocline need the deep suction provided by the to actively bring the oxygen deficient water below the thermocline to the surface to be aerated.

A thermocline also forms in the winter, but it is a reverse thermocline. A peculiar characteristic of water is that it is densest (heaviest) at a temperature just above freezing. Thus, when ice forms on the surface the water below is slightly warmer. Therefore, a reverse thermocline exists. Again, using deep suction to bring the warmer deep water to the surface can keep a portion of the lake and pond ice free. It is usually desirable to remove the nozzle and let the Aerator simply pump at maximum rate without spaying since spraying would cool the water excessively. When a portion of the lake or pond is ice free there will be enough aeration to prevent fish kills from low oxygen levels, and if waterfowl are desired they will need an area free of ice. This de-icing practice is also used where a pond is used as a fire protection reservoir and the water must be accessible and liquid! It is also used to prevent docks and other structures from ice damage.

The 7.5-horsepower Scepter aerator is located in Peru, Illinois has a vertical plume of 25'(h) and 16'(w).

3) Water temperature stratification and low oxygen: Aerators are unique in their ability to directly effect temperature. Temperature plays a significant role in the water quality of a lake or pond. Warm summers and the shallow water cause overall water temperature to rise quickly, resulting in rapid D.O. (dissolved oxygen) drops and unpleasant (odor) conditions. Natural decomposition of accumulated organic matter can lead to reduced water depths and habitat degradation. In its most severe form this thermal layering (thermocline) leads to anaerobic conditions on the bottom and the periodic "turning" or inversion of a lake. The result is typically a "fish kill" that occurs when larger species of aquatic inhabitants can not tolerate both a reduction in D.O. and a temperature increase. Aerators, specifically those with deep suction capability, have the ability to pull water from the lower depths of the system (as opposed to "surface" style aerators), and will prevent stratification with a constant blending of the "water column" to create a uniform temperature throughout all depths. A blending action pulls the cooler water from the depths of the pond or lake, mixing it with the warmer water at the surface, or visa versa in the winter.

4) Ancillary treatments such as Microbial products that reduce nutrients and control algae growth: A complement to aeration is chemical or biological control. As a biologically oriented company, Aquatic Environments strives to investigate every possible alternative to chemical usage for water quality and nuisance vegetation control. In most situations, chemical control is typically the last resort option. When a lake is too far gone or has some other limiting factor (i.e. lack of access for equipment, too large of a system, etc.) then only natural controls can be used. Nature normally controls algae growth with naturally occurring microbes which help to reduce nutrient levels. Unfortunately, under optimum growing conditions, most vegetation and algae can easily outpace the natural bacterial growth. Biological control is the "new" alternative for assisting natural processes.

Microbial treatment is simply the addition of natural, aerobic bacteria in sufficient, regular doses, (often referred to as seeding) to control lake or pond algae by greatly reducing the excessive Phosphorus and Nitrogen in the water. This keeps the microbial colonies in sufficient numbers to consume all available excess nutrients. Bacterial colonies naturally respond to nutrient load in the water system. They will shrink and grow based on nutrient availability. By adding microbes, the level of bacteria is kept artificially high, in anticipation of nutrient spikes. Although the microbes can be added year 'round, typical applications coincide with Spring growth and Fall decline seasons.

The 3-horsepower Crown Gusher aerator has a 12'(h) x 10'(w) pattern perfect for creating a special illumination at night.

5) How flow through helps natural lakes and ponds: Natural lake and pond systems with adequate flow through have noticeably better water quality. However, sometimes nature needs maintenance help in a landscape environment. Flushing, a method of water quality control also referred to as "flow through", creates water movement and acts as a liquid "vacuum cleaner" for the removal of organic matter, nutrients and surface debris. This requires an ample supply of secondary water sufficient to "make up" a water volume. It is unusual to find a situation where water can be exchanged cost-efficiently. Even when adding sufficient water for flushing may not be a problem, removing it may require pumps to augment a discharge equal to the amount of incoming water. Analyze potentially harmful elements in water that is brought into a system: sediment, exotic vegetation or non-native wildlife. In light of these potentially significant problems in natural ponds and lakes, treating a static body of a man made lake with aeration, biologically, or even with chemicals has its advantages!

6) How to specify the Aerator or Fountain for your body of water: Typically, a site inspection by a qualified lake specialist can assist in the correct application and site restraints, and they can provide a detailed checklist that simplifies the process. As part of the Aquatic Environments service, we visit every site to verify conditions and assist the client in the proper site assessment. Based on our experience, we will make recommendations as to type of unit (electrical requirements, vertical or horizontal pump type), application (fresh or salt water) and actual sizing for adequate turnover and horsepower. Other items can also be identified, such as the necessity of suction screens, lights and even types of discharge nozzle features. There is such a thing as an incorrect Aerator or Fountain application, where a unit can be doomed from the beginning. We strongly recommend a call for assistance if you are unsure of the application, by contacting the manufacturer or a local lake specialist in your area.

The 7.5-horsepower two-stage, two-tier Cluster Arch aerator is unique in that the volume of water and large variety of patterns create spectacular art work on the water.

7) How to compare products: Our company goal is to assure that the customer has a reliable solution to meet desired water quality improvements and desired visual effects. It would be a disservice to recommend under-performing units for obvious reasons. As with any product evaluation, we advise purchasers to check all industry certifications and determine past owner satisfaction.

The buyer needs to be particularly aware that some Aerator and Fountain manufacturers have exaggerated their performance numbers. The Aerator and Fountain Division (AFD) of the National Irrigation Association, is attempting to "level the playing field" for the manufacturers of aerators and fountains by providing independent testing and verification for the express purpose of providing actual horsepower to turnover calculations. Most of the more prominent companies (manufacturers) are now members and provide this information in their product literature. However, some of these same manufacturers are unwilling to subject their product to independent testing for reasons we can only speculate. Aqua Control, Inc is willing to provide this corroboration. If you are considering purchasing an aerator then require the manufacturer to provide laboratory corroboration of their pumping and oxygen transfer rates.

8) Volume throughput needed for water size: Under ideal conditions, a body of water should be turned over every day, however, variances such as lake layout, volume, and configuration come into play. For aerators, our advice is to try to size the unit to your water volume first, thus insuring the maximum amount of water volume turnover. The next item, for either an Aerator or Fountain, is to identify the desired pattern in relation to the location and other external factors (i.e. wind patterns or proximity to buildings or windows, etc.). Allow for a "fudge" factor of at least 10' (outside the indicated spray pattern) to account for drift and splash effects.

Another desirable features is the creation of coherent streams to help minimize wind blown spray. All patterns can create spray, so be very aware of that issue. However, Aerators that create very wide, low, patterns do not generate much wind blown over-spray, and a limited number of vertical tier Aerators are so coherent that not much over-spray is created.

9) Performance as determined by HP and flow: In the Aerator manufacturing business, every manufacturer makes claims as to how much volume their unit can move. The problem is: published volume is often significantly greater than reality. This is a very misleading and wasteful tactic, as potential buyers are sizing aerators based on volumes that are often greatly overstated, thus under sizing their Aerators! To avoid this problem, the only aerators our firm will install are those that will provide pumping rate test data from a credible independent lab.

The 1-horsepower Bowl Fountain located in Milwaukee, Wisconsin, is an ideal application for fixed features, eliminating vault constraints and headaches. These fountains come with control panels and can have lighting packages added (as shown). They also work well in retrofit applications due to easy installation.

10) Horizontal versus Vertical Aerator configurations: All Aerator or Fountain applications should begin with a consideration of water depth. The deeper the suction (where the water is pulled from), the better. Vertical deep suction Aerator designs provide the deepest suction and the most benefit for the lake or pond. The typical Aerator design, with suction just under the float, are ineffective for the de-stratification required in deep water applications. In applications where the water is too shallow to allow for a deep draw Aerator, a horizontal draw could be the answer. Horizontal draw aerators allow for circulation and turnover in very shallow ponds. The main benefit of these shallow water units is in creating water movement and turnover in areas that are most susceptible to the ill effects of stagnation. Horizontal applications are ideal for locations that cannot accommodate standard vertical aerators or other means of circulation and aeration. Applications can have as little as 20" of water for a successful Horizontal installation.

11) Run time & reliability necessary to adequately aerate a body of water: Aeration is most effective for water quality when operated at night or in the evening hours when the oxygen demand is at its highest. This does not mean that the unit should only be run at night. For aesthetics, a floating style Aerator is not only a functional addition, but an aesthetic amenity as well. Run it by day for waterscape appeal and run it at night to optimize water quality!

Educating the Consumer

The 3-horsepower Cluster Arch has a 12'(h) x 17'(w) illuminated pattern.

Like it or not, the use of chemicals to control water quality is and will continue to be on the decline. There is no "magic bullet" with regard to chemical control and the future will be in mechanical and biological remediation, and in aeration. Those that have the prior knowledge will be in very good position to proactively address potential problems. Those who do not, will react to problems that have already occurred. We believe that an educated consumer will make a dedicated client, making our job as Lake Managers much easier.

George Forni, President of Aquatic Environments, Inc., (AEI) is an Engineering License holder for aquatic construction, and a certified Aqua Control aerator and fountain specifier and installer with extensive waterscape experience, including projects for The Army Corps of Engineers, Oracle (World Headquarters), the California Department of Fish & Game and the City of San Francisco (Department of Recreation and Parks).