A pond or lake is a very desirable asset for many property owners. With the varied uses of water (irrigation, fish growth, livestock, fire prevention, recreation, waterfowl, wildlife habitat and aesthetics), uses of water sometimes conflict. But no matter what the use, the most important water quality parameter for lakes and ponds is dissolved oxygen. Oxygen is essential to all aerobic (air breathing) organisms. Aeration is one of the most effective lake management tools available and necessary for keeping a body of water healthy. As a result almost all lakes or ponds can benefit from aeration. Below is a list of the top 16 reasons to aerate lakes or ponds based on the experiences of Aquatic Biologists, Inc since our founding in 1977.
PROLONG THE LIFE OF YOUR LAKE
As man's activities bring more and more nutrients into ponds and lakes, the natural production of oxygen and nature's cleansing action have not been able to keep up with the increase. Although added nutrients have increased the aging of ponds and lakes, the use of forced air aeration has proved effective in prolonging their natural life cycles. By supplying your water with greater amounts of oxygen, aeration systems can slow down the natural aging process. Increased plant growth resulting from greater amounts of nutrients cause ponds and lakes to use more oxygen in the decomposition of dead plant life. If the bacteria breaking down the organic matter use too much of the water's oxygen then there will not be enough oxygen for fish life. A proper aeration system provides adequate oxygen for both the increase in decomposition and for fish life.
Many people ask the question, why was my pond or lake crystal clear and free of weeds and algae 20 years ago? The answer to that question is lengthy, most likely nutrient loading is the cause. Decayed weeds, algae, goose manure, and expanding human population contribute to the cause. As more people build homes in a watershed, (all the surrounding land that empties its surface water into a water body), they create erosion problems and add fertilizers to their lawns. Septic systems fail over time and leech nutrients into the watershed. These are just a few of the ways a lake or pond can be affected.
USE NATURE'S CLEANSING ACTION
Aeration takes advantage of nature's own beneficial cleansing process. The only difference is that the natural action is accelerated. The aeration system is based upon the principal of inversion, the complete rolling over of a body of water. Inversion is the natural cleansing action of a water body. This process takes place in the spring and fall when the cooler surface water is heavier than the bottom water and sinks. This is nature's own way of providing oxygen to the water at the bottom and thus removing toxic gases.
As more nutrients enter the water, this natural twice a year process is not capable of keeping up with the increase. As the water is inverted oxygen is pulled to the bottom and toxic gases are blown away at the surface. Again, dissolved oxygen at the bottom is the single most important water quality parameter. Aeration systems rely on the same principals of turn over but on a continuous basis. As bubbles rise from the diffuser, bottom water is pulled to the surface. Surface water then replaces the bottom water. Ideally you should turn over the entire water body 2-5 times a day. Since a single diffuser can only turn over so much water in a 24 hour period, multiple diffusers are used. The number of diffusers that should be used is dependent on the volume of water, water depth, how many times a day the water must turn over and the type of diffuser that is being used.
Goal: Maintain at least 5 ppm oxygen at the bottom sediment layer on a continuous basis. Diffused aeration systems are utilized a majority of the time when this is the objective. The reason for this lies in the fact that more water per horse power can be turned over more economically with diffusers. Fountains use much more horse power when trying to accomplish the same goal. Diffused aeration doe not have moving parts or electrical cables in the water. They also do not create obstacles on the water and are out of site, except for the bubbling action.
Aeration, when used as a management tool is a long term continuous process. Many years of neglect creates an unhealthy pond or lake situation. Aeration must overcome years of organic and nutrient loading and in many instances deal with present loading. The turn around will be gradual. It helps to implement a watershed program that limits present and future loading. This is not easy, but many private individuals and communities have successfully done so.
PREVENT FISH KILLS
Oxygen in ponds comes from three sources - photosynthesis, wind and wave action, and diffusion from the air. The most important source is photosynthesis which is the process plants use for manufacturing food. In the presence of sunlight, plants and algae add oxygen to the water as a by-product of photosynthesis. At night or in the winter, if the ice is snow covered, respiration of fish, algae and bacteria continually remove oxygen from the water. If the oxygen concentration gets too low either in summer or winter you can have a fish kill.
MAINTAIN LARGER AND HEALTHIER FISH POPULATIONS
Maintaining oxygen at the bottom of a lake or pond allows nutrients normally trapped at the bottom to be channeled up through the food chain. These nutrients are taken up and used by aerobic bacteria, microorganisms, invertebrates and aquatic insects, thus increasing the amount of available food for the fish and therby enhancing their growth rate. Harmful substances on the bottom that were dangerous to fish are broken down to inert forms making them unavailable to fish.
By maintaining good oxygen levels throughout the waterway, the living space for the fish is increased allowing for larger fish populations.
INCREASE AVAILABLE FISH FOOD ORGANISIMS
Fish eat just about everything including: detritus, diatoms, aquatic macro-invertebrates (particularly insect larvae, crustaceans and worms), molluscs, aquatic plants, algae, zooplankton, fish and their eggs, terrestrial insects, etc. When oxygen is limited at the soil/water interface these food sources will begin to die. This in turn creates a shortage in the fish population's food supply. By imploying a diffused subsurface or hypolimnetic aeration system oxygen levels at the soil/water interface are increased allowing new insect, larvae, snails, and other fish food to thrive once once more substantually increasing thier availablity as a natural food source for fish.
REDUCE PATHOGENIC BACTERIA COUNTS
Bacteria that cause diseases in humans, animals and/or plants are called pathogenic.There are many types of bacteria found in natural waters both benifical and pathogenic. Most pathogenic bacteria thrives in oxygen-deficent, nutrient-rich environments. By adding aeration a friendly environment is created in which benificial (aerobic) bacteria are able to thrive. The nutrient levels are reduced as well. As a direct result of the higher oxygen levels, reduced nutrient availablity as well as other factors pathogenic bacteria are pushed to a subordinate position by the aerobic bacteria.
Aeration improves water quality and water clarity by impacting three factors; oxygen, nutrients, and temperature. By putting diffused oxygen into the water, aerobic bacteria colonies are encouraged to reproduce and multiply. Aerobic (benificial) bacteria in turn work reduce the levels of dead organic materials, nutrients and other waste. Lastly, a properly sized aeration system will turnover the lake or pond 3 or more times per day causing surface temperatures to decrease while adding dissolved oxygen to the lower regions of particularly at the soil/water interface.
Aeration further improves water quality and water clarity by preventing internal nutrient loading (phosphorus releases from sediments). Phosphorous is further limited with aeration by causing a chemical reaction occur between the dissolved oxygen and the phosphorous. This chemicla reaction converts soluble phosphorus and iron into non-soluble forms that can not be used by plants.
By improving water quality we lower nusciance aquatic weed and algae growth, bottom sludge build up, odors, and insect infestation. In turn this has a positive impact on the environment, and aesthetics. 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.
REDUCE NUTRIENTS
Algae and aquatic plants require many nutrients throughout their life cycles to live and thrive. The primary nutrients they require include iron (for photosyntheseis), phosphorous (for producing enzymes), manganese (for chlorophyll production) along with nitrates and nitrogen in a fixed, water soluble form.
Of these nutrients, phosphorous is considered the primary trigger for most nuisance algae growth (Total phosphorous levels above 0.03 ppm are known to fuel abundant algae growth). Once phosphates enter a pond they are almost impossible to remove. The best option is to bind them through aeration or with Bio Boost Phosphate Cleanser. Phosphates can be bound to cations (positively charged ions present in the water) if sufficient oxygen is present. Once bound to the cations, the phosphorus is precipitated out of the water column and into the bottom sediment. The phosphorus is unavailable for algae growth as long as oxygen levels are sustained. The same is true of iron, manganese, nitrates and nitrogen.
Biological processes occur within a pond or lake. They are too vast to discuss all of them. Here are 2 of the most beneficial attributes of aeration. Microscopic organisms, predominantly bacteria, decompose organic matter and use available phosphorus for energy and reproduction. They will accomplish these feats aerobically (in the presence of oxygen). Without oxygen, anaerobic bacteria produce hydrogen sulfide (rotten egg smell), methane and ammonia. All of which are unhealthy to living organisms. Bacteria are also important and necessary for converting nitrogen ammonia to nitrate. The safe form of nitrogen.
BIO-AUGMENTATION
Bacteria and enzymes can be added to accelerate the digestion of organic material and digest nutrients essential for undesirable algae growth. Beneficial bacteria are added to a pond in powder, packets, or liquid form. Upon contact with the water, bacteria come to life. They help decompose waste products and assimilate nutrients by converting this material to other bacteria through the process of growth and reproduction. Bacteria then become the food source for other aquatic organisms. They are the beginning of the food chain. Enzymes are used to facilitate the growth of bacteria and aid in the breakdown of organic materials. To learn more or purchase these all natural products, consult an ABI representative or click on our Biological Treatment Products page.
Reduce Harmful Gases (NH3, CO2, CH4, H2S)
Lake Eutrophication begins when the BOD (Biological Oxygen Demand) of a lake cannot be met causing vast amounts of aquatic plant and algae growth to die. As the plants and algae die they sink to the bottom of the lake or pond to be decomposed by benthic invertabrates. This influx of decomposing vegetation to the sediment/water interface depletes dissolved oxygen creating an anaerobic environment. When oxygen is depleted in a water body, anaerobic bacteria partially break down the sediment. Anaerobic bacteria produce deadly poisonous gases, such as carbon dioxide (CO2), hydrogen sulfide (H2S), ammonia (NH3), and methane (CH4). These gases, rise through the water, uniting and binding any dissolved oxygen remaining in the water.
Hydrogen sulfide is produced by anaerobic (without oxygen) bacteria breaking down organic matter in the bottom of the pond. The pond bottom has less oxygen than the upper layers of the pond especially if you have stone or gravel in the bottom of your pond. Hydrogen sulfide is not only highly toxic to aerobic or good bacteria; it is also toxic to insects and fish at levels of 0.3 mg/l (a very low amount).
The anaerobic (bad) bacteria also release ammonia, nitrogen gas and carbon dioxidie into the water column. Ammonia feeds weeds and algae and is toxic to fish at levels greater than 3.0 mg/l. Carbon dioxide and methane kill fish at levels greater than 30 mg/l.
When aeration inverts and oxygenates a body of water, the anaerobes die and noxious gases are no longer produced. At the same time the hydrogen sulfide, ammonia, nitrogen, methane and carbon dioxide already present throughout the water is quickly exhausted to the atmosphere, where it is neutralized and eliminated.
INCREASE BENIFICAL AEROBIC BACTERIA
By introducing oxygen to the bottom of your lake or pond, aerobic bacteria as well as other benthic organisms will be able to exist and eat away at the organic matter that has accumulated over time. Aerobic bacteria grow and eat 30 times faster than anaerobic bacteria. During this digestion process, CO2 is formed and if properly aerated is pushed up to the surface and released into the atmosphere. If the aeration is not adequate, the CO2 will be mixed into the water column and along with water and sunlight will enable aquatic plants and algae to thrive. In short, aerobic bacteria will digest the same amount of dead organic material in one year that anaerobic bacteria take 30 years to digest!
Large build-ups of organic sediment, sludge, or muck are commonplace in many water bodies. This is the result of years of nutrients and organic matter entering the pond water through runoff containing fertilizers, grass clippings, animal waste, septic waste, etc. Also, leaves dropping or blowing into the pond. All of the above contributes the majority of this organic material, but aquatic weeds, algae, dust, pollen, fish and waterfowl droppings are also contributors.
Aeration systems sustain oxygen levels keep dissolved oxygen levels present throughout the water column at all times Only when sufficent amounts of dissolved oxygen is present will beneficial bacteria and insects feed on the organic sediment. The bacteria feed on the organic sediment, and the insects feed on either the bacteria or the muck, or both. The bacteria convert organic sediment into carbon dioxide and water and a microscopic amount of inorganic “ash”. In this process, the good bacteria exude an enzyme to break down the cells of waste material in order to consume the various types of muck within the sludge layer.
INCREASE DISSOLVED OXYGEN LEVELS
Dissolved Oxygen (DO) is the most important water quality parameter concerning aquatic life in lakes and ponds. It is a measure of the amount of oxygen dissolved in the water that is available for aquatic life and is typically measured in Parts Per Million (PPM). To put this in persective our atmosphere is 20% oxygen or 200,000 ppm. A pond or lake will seldom have more than a maximimum of 10 ppm dissolved oxygen.
Oxygen dissolves into water from two sources: the atmosphere and from plants in the water. Dissolved oxygen levels fluctuate with the time of day and the activities in the pond. During the nighttime hours, plants stop producing oxygen in the photosynthesis process and actually start using up oxygen. Fish and aquatic life activity such as feeding also uses up dissolved oxygen in the pond. Another large dissolved oxygen user is bacteria. During the decomposition process, bacteria use oxygen to breakdown organic material. During a plant or algae die off, decomposition rates greatly increase and so does the demand for oxygen. This can drastically drop the dissolved oxygen rates and cause fish die off.
Oxygen depletions are the most common cause of fish kills in lakes and ponds. Dissolved oxygen concentrations below 3 ppm stress most warmwater species of fish and concentrations below 2 ppm will kill some species. Cold water has the ability to hold more dissolved oxygen than warm water. Most oxygen deletions occur in the summer months because 1) warm water holds less dissolved oxygen than cool or cold water, and 2) because the pond's oxygen demand is greater in warm water than in cold water.
Aeration systmes may be used to prevent winter fish kills and protect permanent fixtures in your lake or pond. During harsh winters the heavy snow and ice prevent sunlight from penetrating into the water causing existing aquatic vegetation to die off. As the vegetation dies, the decomposition process uses up much of the available oxygen in the pond. As the winter progresses, the oxygen levels continue to decrease and eventually, your fish may begin to die. An aeration system will mix the water and move warmer, bottom water to the surface to keep an area of the pond open.
Open water is also desirable for water fowl and fishing. Aeration during the winter, without open water, can also be obtained through the use of our floating ice domes.
By adding adequate air to the bottom waters, gases from decaying organic matter can be exhausted from the soil/water interface. The stagnant rotting egg odors found in many ponds and lakes can be completely eliminated.
MOSQUITO CONTROL
Mosquitoes prefer stagnant water. Aeration will also increase fish and other invertebrates that feed on mosquito larva.
Aeration increases the management options for lake and ponds. These options will very depending on what the pond is to be primarily managed for (i.e. fish, swimming, aesthics, etc.). Please contact ABI to discover how aeration will increase your lake or pond's overall management in the future.