At Mid-Michigan Ponds, we offer a complete line of management supplies and services. We understand that no two ponds are alike; so we specialize in tailoring solutions that work best for your pond's specific needs.
We'll come out and evaluate your pond, then develop a strategic approach to keep your pond clean and healthy. From full-service pond maintenance programs, to equipping the pond owner for a more do-it-yourself approach, we'll make your pond a valuable and beautiful part of your property.
Pond and Lake Ecology 101
Before getting into pond management strategies, let's first cover some basic pond ecology.
Euthrophication is the natural aging process for lakes and ponds. As a lake or pond ages, it slowly starts to fill in with organic material such as decaying aquatic vegetation, dead fish, leaf litter, trees, etc. However, this slow process is greatly accelerated when we add additional sources of nutrients to the ecosystem. Goose manure, fertilizer runoff from lawns, agricultural runoff, failed septic systems and erosion problems are some of the main causes.
Dissolved oxygen (DO) is the form of oxygen that fish and other aquatic life need to stay alive. It is the single most important water quality parameter. Plants produce through photosynthesis about 75% of a pond's DO supply. The remaining 25% comes by absorption of oxygen from the atmosphere. Depending on the species, most fish need at least 4ppm DO to survive.
Thermostratification is the process where lakes naturally stratify into three layers based on temperature. The top layer can sometimes by 10 to 15 degrees warmer than the bottom. The middle layer (called thermocline) is a thin zone where the temperature changes quickly. Once these layers become established, density differences prevent the top and bottom layers from mixing and exchanging DO. All the DO producing is confined to the top layer, so as the summer progresses the bottom layers become stagnant and depleted of DO. Anaerobic bacteria start building up harmful levels of hydrogen sulfide (smells like rotten eggs), ammonia and methane.
Nature's Way of Pond Management
Inversion is the natural cleansing process of a pond or lake. It occurs in the spring and fall when the cooler water at the surface is heavier than the bottom water and sinks. This is nature's way of supplying oxygen rich water from the surface layer to the stagnant water at the bottom. The oxygen drives off toxic gases that build up in the bottom layer. It also revives the aerobic bacteria population so they can start decomposing the organic litter that has built up.
Eventually the microbial activity will use up this fresh supply of DO and the bottom layer will again return to its stagnant condition until the next inversion occurs. Dissolved oxygen at the bottom of the pond is the single most important water quality parameter that drives nature's cleansing process. Unfortunately, this twice a year process is not enough to keep up with the build-up of organic material and when even more nutrients are added to the ecosystem the pond or lake starts filling in even faster.
Pond Aeration: The Long-term Solution
Aeration systems rely on the same cleansing principles of inversion, only the DO is circulated continuously. Instead of inverting a pond twice a year, a properly designed aeration system will invert a pond up to several times a day. By using various types of compressors, an aerator pumps atmospheric oxygen down to a weighted diffuser. The diffuser releases oxygen to the stagnant bottom layer and sediments where it is needed most. As the oxygen bubbles to the surface, it creates a slight current that lifts the stagnant water off the bottom and brings it to the surface where it gets cleansed with oxygen and healthy microbial activity. This current creates circulation (or inversion) constantly bring fresh water down to the bottom where it is needed, as well as throughout the entire pond. Maintaining high DO levels throughout the pond and especially the bottom is the key to a healthy ecosystem.
Pond Aeration Long-term Benefits
Extend the Life of Your Pond
Maintaining a healthy level of DO at the bottom of the pond allows aerobic bacteria and other microbes to aggressively decompose the organic litter build-up on a continous basis. This will slow down the euthrophication process and extend the life of your pond.
Improved Water Clarity
Water is often discolored or murky from suspended organic particles. Aeration establishes healthy levels of DO throughout the entire water column. This promotes healthy strains of aerobic bacteria that will break down these particles resulting in improved water clarity.
Reduce Weeds and Algae
Phosphorus, nitrogen, and carbon are the main cause of nuisance algae blooms. When high levels of DO are maintained, naturally occuring aerobic bacteria compete with the weeds and algae for these available nutrients. They use the nutrients for growth and reproduction. These bacteria then become food for other organisms that bioaccumulate the nutrients into the food chain for the fish. So not only does aeration help reduce the nutrients available for plants and algae, but it also converts those nutrients into a form that promotes a better fishery.
Very little phosphorus is needed to support algae blooms, and once phosphorus enters a pond's ecosystem it is very difficult to remove. In addition to reducing the sources of input, the best approach is to bind the phosphorus up so that it is not available for the plants and algae. Aeration accomplishes this by causing the phosphorus to precipitate out with naturally occuring iron. This oxidation reaction only occurs in the presence of DO. Once bound to the iron, this new form of phosphorus precipitates into the sediments where it remains unavailable for plant and algae growth as long as sufficient levels of DO are maintained.
Reduce or Eliminate the Need for Chemicals
By targeting the source of the problem, not just the symptoms, the need for applying sometimes harmful chemicals to your pond is greatly reduced, saving you time and money.
Promote Healthier and Larger Fish Populations
Adequate supplies of DO at the pond bottom means an increase in the amount of area fish can inhabit. When the bottom layer of a pond is depleted of DO and high in ammonia and hydrogen sulfide, the fish population is confined to living only in the warmer upper layer. In late July and August, this layer often gets too warm for the fish and they become stressed. This results in slower growth and a higher susceptibility to disease. Aeration eliminates the layering, and allows the fish to utilize the entire pond. Now the bottom is a healthy ecosystem that supports aerobic bacteria, microorganisms, invertebrates and aquatic insects. This provides an additional food source for the fish, and results in a healthier population with better growth rates.
Prevents Summerkill and Winterkill
During the winter, ice forms a seal at the surface of the water and prevents the pond from receiving oxygen from the atmosphere. Plants will continue to photosynthesize through the ice until snow blocks out the sunlight. When this happens, the plants begin to die and decay causing even higher demands on the now limited supply of DO. If the pond already has a high biological oxygen demand (BOD) due to conditions such as excessive organic material in the bottom or banks, DO concentrations can be reduced and harmful gases increased to levels that result in a partial or total fish population die off.
By late July or early August the DO levels get depleted near the bottom and the fish get confined to living in the top layer. DO production is highest in the late afternoon following a full day of photosynthesis. During the night, DO production stops, but DO consumption (or BOD) continues and starts to deplete the DO reserve that was built up during the day. This results in a delicate balance of supply and demand. The lowest levels of DO occur in the morning around sunrise, so if you see fish swimming close to the surface in the early morning, your pond is probably a good candidate for a summerkill. What causes a summerkill to occur are events that tip this delicate balance by either decreasing the DO production or increasing the BOD. The four most common cases are:
- Extended days of cloudy skies with little wind.
- Excessive amounts of nutrients entering from runoff triggering algae blooms that cover the surface of a pond. A sudden die off of the algae results in a big increase in the BOD.
- Thunderstorms that produce heavy downpours of cool rain and strong winds can result in an inversion or mixing of the top layer with the stagnant bottom layer. This mixing results in low DO levels and often toxic levels of hydrogen sulfide, ammonia and/or methane gases throughout the pond.
- Improper application of aquatic herbicides. Killing too many plants and/or algae at one time leads t a dramatic reduction in DO production and the decaying plants increase the BOD.
Aeration prvents winterkill and summerkill by creating good circulation and maintaining high levels of DO throughout the pond. Creating a healthy ecosystem on the bottom also prevents the build-up of toxic gases.
Mosquitoes thrive on calm, stagnant water. Aeration reduces their breeding success by keeping fresh water circulated.