Pond Aeration and Lake Aeration - Frequently Ask Questions (FAQs)
1. What are the benefits of pond aeration?
The benefits of pond aeration a numerous. The overall extent of improving water quality will largely depend upon how eutrophic your pond or lake originally was prior to aeration. Aeration is used to artificially circulate ponds and lakes in order to increase dissolved oxygen concentrations in deeper waters. Ponds and lakes that thermally stratify during the summer will completely mix when aerated. This will result in nearly uniform water temperatures from the surface to the bottom of the pond or lake.
One benefit of aeration is the reduction of iron and manganese problems for drinking water supplies. Iron and manganese can be released from lake sediments under anoxic conditions in stratified ponds and lakes and artificial circulation via aeration can reduce this phenomenon.
Another potential benefit of aeration is to improve water transparency(clarity) by reducing the amount of phytoplankton(free-floating microscopic aquatic plants or algae). Lastly, aeration may even reduce the amount of accumulated muck in ponds and lakes. This may occur by oxygenating deeper waters near the sediments. Under such conditions, bacteria metabolize(break down) organic matter much more quickly.
Phytoplankton reductions resulting from aeration are based upon a series of complex physical, chemical and biological reactions. Some of the current theories are as follows:
A. Increased dissolved oxygen concentrations in deeper pond and lake waters will decrease the release of phosphorus (and metals) from sediments. Lower phosphorus concentrations provide less food for algae growth.
B. When the water column is mixed, phytoplankton are pushed into the deeper water. This may result in lower growth and reproduction rates for the phytoplankton due to lower rates of photosynthesis in darker waters.
C. Zooplankton (barely visible to the naked eye, tiny aquatic animals that feed upon algae or phytoplankton) are pushed into deeper waters due to pond and lake mixing. In darker waters, they are less vulnerable to sight feeding fish such as, juvenile bass, bluegill and crappie. Under such conditions, zooplankton survival rates are expected to increase, which in turn translates into higher predation rates on phytoplankton (algae).
D. Rapid circulation of carbon dioxide-enriched bottom waters with surface waters and contact with the atmosphere may increase the carbon dioxide content and lower the pH of the surface waters. This encourages the growth of less noxious green algae as opposed to blue-green algae.
2. Which is better for aerating my pond: a fountain vs. pond aerator (bubbler or diffused air aerator)?
Fountains (water fountains, pond fountains, floating fountains, pond aerators, lake water fountains, and lake fountains) are primarily installed as water features to enhance the appearance of ponds and lakes. Water fountains may increase water circulation in smaller, shallower ponds. Under such conditions, water fountains may increase dissolved oxygen concentrations and possibly decrease the amount of phytoplankton (free-floating microscopic aquatic plants or algae). Water transparency (clarity) may even improve if phytoplankton levels drop significantly. However, if water quality improvements are the primary objective, a pond aerator (bubbler, diffused-air aerator) like a Hydro Logic AirLift pond aerators is recommended. In some instances, our customers install both a bubbler pond aerator for aeration and a fountain as a water feature plus aeration.
3. What is the best air compressor for pond aeration or a pond aerator?
There are several types of air compressors (air blowers, linear, diaphragm, rotary vane, piston and rotary screw) known by various names (aerator pump, pond bubbler, pond aeration pump, diffuser pump, water aerator, septic aerator) that are commonly used as pond aerators and lake aerators. Of these types, piston air compressors are the best all-around choice for ponds and smaller lakes.
Piston air compressors are highly durable, very reliable and extremely cost-effective when it comes to producing high airflow volumes under pressure. This is why dual piston air compressors can be placed in water depths exceeding 40 feet. In many instances, smaller diameter air supply tubing, which connects the air compressor to the air diffuser (e.g. AirPod), can be used in many installations. Smaller diameter air supply tubing is less expensive and much easier to install. Conversely, linear, diaphragm and rotary vane compressors should only be used in shallower ponds and lakes (generally less than 10 feet in depth) because they are not capable of producing high air pressures and may eventually burn-up the motor. In addition, these other types of air compressors typically require larger diameter, heavier air supply tubing to account for air pressure drops. Larger diameter, heavier air supply tubing is more expensive and more labor intensive to install.
On a per horsepower (HP) basis, dual piston air compressors simply out-perform standard rotary vane air compressors. For example, a standard ¾ HP (0.75 HP) rotary vane air compressor produces airflow of 8 scfm (standard cubic feet per minute) at open flow (0 psi) and 6.8 scfm at 10 psi (pounds per square inch). Conversely, standard dual piston air compressors (0.66 HP) produce airflows of 9.8 scfm at open flow and 9.0 scfm at 10 psi! This simply means that you obtain more air for less money and have the option to use smaller lighter tubing due to the higher pressure rating of the piston compressors.
Lastly, high air pressure allows rubber air diffusers (e.g. AirPods) to be easily cleaned from the shoreline. Simply allow the compressed air from the compressor to flex the EPDM tube air diffuser to dislodge any mineral deposits, algae and sediments from its surface. Unfortunately, other air compressors (linear, diaphragm, rotary vane) cannot deliver sufficient airflow under pressure to adequately inflate (flex) the EPDM tube air diffuser for proper cleaning. For these other aeration systems, the pond or lake owner must launch a boat; pull up the entire air diffuser base to the surface of the pond or lake; scrape off the debris; and rinse the air diffusers with a concentrated acid solution. This is exactly the reason the manufacturers of rotary vane compressor aeration systems insist that you run them year-round - basically doubling the operating costs.
4. What is the best pond air diffuser for pond aeration or a pond aerator?
The newest, most innovative technology in pond and lake aeration is the use of EPDM rubber air diffusers (AirPod and AirPod XL air diffusers by Hydro Logic). EPDM rubber air diffusers are commonly used in aerating and treating municipal and industrial wastes. EPDM rubber air diffusers produce very fine bubbles, which provide better water mixing in pond and lakes); are less prone to clog up; and are essentially maintenance free when compared to air stones and micro-porous media air diffusers.
The manufacturers of pond and lake aeration systems equipped with air stones and micro-porous media air diffusers recommend cleaning their air diffusers at least once per year. This means launching a boat; pulling up the entire air diffuser base to the surface of the pond or lake; scraping off the debris; and rinsing the air diffusers with a concentrated acid solution. In addition, these same manufacturers typically recommend operating their aeration systems year round to avoid clogging up their air diffusers. Year round aeration may be necessary for ponds and lakes in the southern states with longer growing seasons, but this is generally not the case for ponds and lakes in the northern states. We often recommend aerating northern ponds and lakes from April through September or mid-October. Winter aeration is only recommended if the water body has a history of having fishkills when ice forms.
Conversely, EPDM rubber diffusers will not clog when aeration systems are shut down for extended periods of time. This is because the tiny slits in the rubber membrane completely close and subsequently cannot clog. There are two types of EPDM rubber membranes – round discs and tubes. We use EPDM rubber tube air diffusers, which are simply much more durable than the round discs. Overall, the EPDM round disc rubber membranes are more prone to failure where the rubber discs frequently tear away from its plastic housing.
5. AirLift vs. AirLift XL Series: Which is the best choice for my pond or lake?
The AirLift Series can be used in both shallow and deep ponds and lakes (greater than 40 feet deep). An excellent choice for all ponds and lakes!
In contrast, if project budget becomes a concern, the AirLift XL series is a terrific choice for deeper ponds and lakes (water depths exceeding 15 to 20 feet deep). This allows customers to install less air diffusers (AirPods) and less aeration tubing (DownUnder tubing) resulting in an overall lower project cost. The main reason that fewer air diffusers can be used in deeper ponds and lakes is because the process of aeration becomes increasingly more efficient as water depth increases.