The term "surface aerator" should not be confused with the zone for which an aerator provides aeration. It simply means the location in which such a device is installed i.e., at the surface of a pond or lake, supported commonly by a floatation device. However, some devices may be rigidly mounted. The equipment for this type of aeration is the floating type, and therefore is better termed "floating aerator." Mechanical aeration can be achieved by two methods: 1) Placing air into the water (Bubblers or diffused air systems) 2) Propelling water into the air Propelling water into the air is the most efficient method for aerating water. Propelling water into the air can be achieved by the use of display (fountain) aerators or by using non-display type aerators. The display (fountain) aerator affords aesthetics as well as aeration. The non-display type aerator, while less costly for capital outlay, is the most effective for aeration. However, it may be considered to be less attractive. Remember, "beauty is in the eye of the beholder," and is probably best left up to the potential user. Conversely, there are non-aerating display type fountains that, although attractive, may not produce enough aeration to make any biological impact on a lake or pond. Although the water that is placed into the atmosphere may be aerated, the result will not improve the oxygen level in a pond or lake. This is due to the fact that the number of gallons of water per minute being ejected into the air is not sufficient enough to make any measurable improvement of the oxygen levels compared to the overall body of water. Therefore, this type of unit is not recommended for aeration. In situations where both aeration and aesthetics are desired, a combination of both types can be incorporated to provide an aesthetic balance. It is important to note that there are aerators that float on the surface of a body of water that have incorporated the use of what is commonly called a "draft tube." Draft tubes pull water from depth, bringing the water to the surface to be exposed, so that the oxygen in the atmosphere can be transferred to the parent body of water. It should also be understood that there are no differences in whether water movement in ponds and lakes is circulated in a latitudinal or in a longitudinal direction. It has been stated that the use of a draft tube is the proper way to provide aeration for a floating aerator. This concept deserves further clarification. A draft tube is only one option for an aerator?EUR??,,????'???s design. It does not ensure that the aerator will actually circulate the entire lake or pond. The American Society Of Civil Engineers (ASCE) has developed a "Standard of Practice" oxygen transfer test. This test was designed to provide a level playing field in determining the aerator?EUR??,,????'???s performance and is to be certified by a licensed Professional Engineer. The results are expressed as S.O.T.R. (Standard Oxygen Transfer Rate) Since most of the existing ponds and lakes may have islands or dog legs, etc., and are not engineered to take full advantage of fluid hydraulics, the S.O.T.R. numbers should be used for comparative purposes so that the informed equipment selection can be made. Always take into consideration capital cost, cost of operation and the ease of maintenance. To truly be an effective aerator, the aerating device should have sufficient unencumbered pumpage so as not to interfere with the discharge of the water to atmosphere. It should also operate with as high a volume of water as is possible and practical. Nozzle orifices of any size will restrict water flow due to friction losses that naturally occur. Whenever a deflector or nozzle is placed over or around the propeller a restriction will form that will minimize the ability of a device to pump water and aerate. It is important that this restriction be engineered to a minimal restriction and designed to enhance the aerator?EUR??,,????'???s performance. Care should be taken to ask the right questions when evaluating a particular device for implementation into a given scenario. Ask the following questions: ?EUR??,,????'???? Is the device ASCE-certified for its aeration ability? ?EUR??,,????'???? Has each spray pattern and horsepower been tested to ASCE standards? Also, don?EUR??,,????'???t be afraid to ask for the printed data on the ASCE certification. If the above questions cannot be answered satisfactorily, you can assume that the device has not been certified, or that it does not perform as well as an aerator and may only be aesthetically pleasing. The manufacturer and associated dealer/distributor should be able to assist you in the selection of the appropriately sized aerators or fountain aerators for your pond or lake by asking you a few questions. It should be noted that a pond or lake does not need to be 100 percent aerated -- trying this would probably be a waste of electrical energy and equipment expense. Fountain equipment meant for aesthetic purposes does not require the technical aspects (aeration capability) of a particular design, since aeration is not the primary interest. Bottom line: there are different aeration systems designed to meet the needs of specific pond and lake water situations. Don?EUR??,,????'???t be lulled in to the theory that the draft tube design is the only system that can improve the water quality for a pond or lake. In order to choose the right aeration system: ?EUR??,,????'???? take the time to ask a reputable dealer or distributor a few questions ?EUR??,,????'???? understand your maintenance abilities ?EUR??,,????'???? assess your capital resources ?EUR??,,????'???? determine the equipment?EUR??,,????'???s ease of use ?EUR??,,????'???? ask about warranty coverage, service, and repair procedures. ?EUR??,,????'???? Base your final decision on the system that most efficiently and effectively works best to improve the quality of the water. The desired results are a high standard oxygen transfer rate, a reasonable equipment cost and an understandable knowledge of the serviceability of the equipment. Air-O-Lator Corporation has been a manufacturer of aerator mixers and fountains since 1967. For more information visit www.airolator.com.