|Frequently asked lake* aeration questions:
1. What is the difference between surface and submersed aeration?
Within the industry, a surface aerator is a device that takes water from the vicinity of the surface and throws it into the air, where it picks up atmospheric oxygen. Submerged aeration typically uses air bubbles that are released below the surface and give up the oxygen they contain as they rise. Another method is the Synergistic Technique. It destratifies and puts oxygen on the bottom where it will improve the overall water quality of the lake. Surface aeration is excellent in an emergency. It can quickly put a lot of oxygen in a small area where the fish can come to survive. Never use submerged aeration systems in an emergency, as the oxygen put in is diluted throughout the water column and the higher oxygen levels normally found on the surface are made lower by upward pulsing bottom water.
2. Will aeration control algae and weed problems?
Algae obtain their nutrients from the water, while submerged weeds typically obtain nutrients from root systems in the soil of the lake bottom. Aeration would have no effect on the rooted plants, but it can have a profound effect on the algae, depending upon many circumstances. In the right situation, a well-designed aeration system will greatly reduce algae primarily by reducing nutrient cycling from the formerly anaerobic bottom. As the water clarity improves, the plant community may shift to submerged weeds.
3. How does aeration put oxygen into the water? At what rate?
Lake aeration devices, from surface aerators to synergistic airlifts, put oxygen into the water between the rates of 1-10 pounds of oxygen per horsepower per hour (.6 - 6.0 kilograms per kilowatt). Fountains are at the low end of the oxygen transfer rate, as they expend much more energy putting on a show than they do transferring oxygen. Synergistic airlifts are at the other end of the spectrum because they expend very little energy and circulate huge quantities of water upward. In this case, the interaction at the surface of the lake adds to the majority of the oxygen added to the water.
4. Will aeration improve water quality and clarity?
Only when aeration is done correctly will it improve water quality and water clarity. All lakes are different and they often need an engineered approach. When a stratified lake is destratified, water quality is improved by reducing the nutrient cycling and increasing the assimilation capacity. In some lakes with very clear surface water, destratification can reduce water clarity.
5. How long will it take for aeration to improve a lake?
In general, the time will vary between 2 and 12 months before visually significant improvements are reached. If the lake is a good candidate for aeration, and if the aeration system is designed correctly, it will definitely continue to improve the water clarity year after year, unless more nutrients are added.
6. Why is the synergistic diffuser manifold more efficient at deeper depths?
It is not efficient at shallow depths because of the short distance between the low-pressure and high-pressure areas of the water column. Since high pressure will flow to low pressure, the close proximity of the boil at the surface to the low-pressure "suction" at the bottom causes a short circuit. In a deep lake, the distances between the high pressure and the low are too great for this effect to take place.
7. How loud is a Great Lakes® system?
All of our cabinets have been designed to provide significant sound attenuation and, in most cases, the noise level is below 55 dB at ten feet and inaudible 50 feet from the cabinet.
8. Does the aeration system have to run continuously?
Yes. We design all of our systems to be small in size and to operate continuously, as opposed to a large system that operates intermittently. However, they can be shut down completely or intermittently during cold months.
9. Can the Great Lakes® system be used during the winter?
This depends upon how cold the area gets. If the water gets cold and the bottom D.O. remains above 5 ppm, the system can be turned off. When very cold, the rate of oxygen consumption is so low that the lake can be satisfied without the aid of an aeration system. If the lake ices over briefly and does not have a history of winter fishkill, the system can be turned off. If the lake freezes hard and has a history of winter fishkill, a small portion of the summer aeration system can be operated during the cold months. Remember that an open hole will exist in the ice around a diffuser boil and can pose a danger to people and animals, especially at night.
10. What is the maintenance for the Great Lakes® system?
Depending upon conditions, typical maintenance consists of quarterly checking and cleaning of the air filter, replacement of carbon vanes in 9-12 month intervals and cleaning of the diffusers as necessary after about three years. Sometimes, after three years, either the entire compressor or its motor bearings should be replaced. AES provides factory-rebuilt units and ships the same day.
11. How much will it cost in electricity per month?
One horsepower, running continuously at a rate of ten cents per kilowatt hour, will cost $72. One-half horsepower will cost $36. One-third horsepower will cost $24. The cost may be less because of lower electric rate and actual power consumption.
12. Should bottom aeration or surface aeration be used in a lake where trout are raised?
Trout generally require water colder than 68°F (20°C). If the surface temperature of the lake in the summer does not rise above this temperature, then bottom aeration will work fine. If the surface temperature goes above 68° in the summer and the cold bottom layer of the lake does not have sufficient oxygen at the end of the summer to support the trout, then neither type of aeration would be applicable. Either a hypolimnetic aeration system or a pure oxygen system adding to the bottom strata only would have to be used (AES can design both pure oxygen systems and hypolimnetic systems).
13. How long does it take to install the system?
The most difficult part of installing an aeration system is getting the electricity to the site. The good news is that, generally speaking, the air compressor can be placed near an existing electrical location and the air line(s) can be run from that point to the lake. HeavySet® tubing can be used from the water's edge to the diffusers. This tubing can be laid out just as fast as a garden hose can be uncoiled. Some care is required in lowering the diffuser manifold from the boat. Include time for trenching airlines into the ground and pouring a small concrete pad for the compressor cabinet (if desired).
14. What is the difference between a 4- and a 6-diffuser manifold?
The 4-diffuser manifold is designed for shallow applications where more manifolds are needed because of the shallow water short-circuiting (see #6). A 6-diffuser manifold lifts significantly more water in deep applications. Eight-diffuser manifolds are available for very deep applications.
15. If a 6-diffuser manifold is required for depths of 8' or greater, how can a 4-diffuser manifold be used on a DA1A aeration system in water up to 20' deep?
The smaller aeration system is not as efficient at this greater depth, but it is adequate because the pond is small. More horsepower would be needed to run a large diffuser, which would be oversized for the pond.
16. Will the diffuser manifolds stir up mud on the bottom of the pond?
They will not, if the underlay included on all the Great Lakes® manifolds is used. Be sure that the underlay is installed flat on the bottom. The sediment that rises to the top at initial start-up is just the very loose sediment that was disturbed in the area where the diffuser was placed.
17. How many diffusers should be used?
Call to talk with our Lake Department experts, who will provide a free recommendation. You should complete our Ponds/Lakes Aeration and Water Quality Questionnaire here before calling, or you can send it in by mail, e-mail or fax.
18. How far apart should the diffusers be placed?
As a general rule, the diffusers should be an equal distance from each other and from the shore. However, the bottom contour can greatly alter this general rule. Mail or fax a sketch for help from our experts.
19. Can ozone be run through this system?
Yes, when it is injected after the air compressor. However, we do not recommend its use in natural lakes. If you were to use the appropriate amount of ozone for the BOD and water volume, you would kill many organisms necessary to a natural lake.
20. If I live on a large lake, can I just aerate my backyard portion?
In most cases, this would not have a beneficial effect on the lake in total. If a diffuser were placed above the thermocline, it would induce circulation and act as an artificial structure that would be a fish attractor. If the diffuser were below the thermocline, it would be lifting some of the coolest, heaviest, worst quality water and putting it on the surface in front of your property. For aeration to be effective in the overall water quality improvement of the lake, it has to be designed for the entire lake or a hypolimnetically isolated portion of the lake.
*As it applies here, we define a lake as a water impoundment larger than one acre and a pond as less than one acre. A garden pond is typically less than 1/10 acre.