Pond Management

Ponds, like lawns or gardens, require routine maintenance. It is important to monitor conditions and take corrective action early before expensive problems develop. Unquestionably, the most misunderstood need for maintaining ponds is adding lime. Satisfying the lime requirement of pond bottom mud improves productivity, appearance, water quality, and consistency.

Most ponds in the Southeast need lime. We have acidic soils, acid rain and acidic runoff from decaying leaves and pine straw. Lime generally improves the overall health of ponds. Fertilizing is much more effective if the pond mud has the proper amount of lime. Ponds usually need as much lime as nearby cropland. Lime buffers the water to prevent stressful fluctuations in water chemistry. Ponds requiring lime may have drastic changes in pH (relative acidity) from morning to evening on a bright sunny day. Lime also helps clear muddy ponds by encouraging the sediment to settle out more quickly. To determine the pond's lime requirement, scoop mud from deep as well as shallow parts of the pond. We use a special bottom dredge and collect samples in an "S" shaped pattern over the entire pond. Mix the mud samples thoroughly in a clean plastic bucket. Spread some of the mud on plastic to dry. Have a portion of the sample analyzed to determine the lime requirement. We send samples to a lab in Ohio. They tell us exactly how much lime is needed in a recreational fishing pond. Most ponds we check require 2 - 3 tons of agricultural lime per acre initially. An additional 1 - 2 tons per acre is required each 3 - 5 years afterward. An exception to the need to lime a pond is when swimming is the primary objective for the pond. Clear, unproductive water is generally desirable for swimming.

Fertilized ponds have a deep green color which prevents light from reaching the bottom. Nuisance weeds and algae begin growing on the pond bottom and are inhibited when light cannot reach them. Research has shown that liquid pond fertilizer is less expensive and more effective than granular fertilizer. One gallon per acre of liquid polyphosphate (10 - 34 - 2 or similar) should be applied in late February or early March. Another application should be made whenever a Sechi disk (or black and white object 6 - 8 inches in diameter) can be seen in water deeper that 18 inches. Applications should continue until September. Most ponds require 4 - 6 applications of 1 gallon/acre each year. If two or three fertilizer applications do not limit light penetration to less than 18 inches, the pond probably needs lime. The fertilizer is not being utilized.

Colorants are available which shade the bottom by reducing light penetration in water. Treated water is an attractive blue color. Many of our customers begin using the colorants to inhibit plant growth, then continue because they like the appearance. The colorants are non-toxic and safe for animals drinking the water. Dry colorant powder is available in packets which dissolve, too. The colorants can be added at lower concentrations (about 1/4 of the recommended rate) to improve the appearance of muddy ponds. They don't improve the water quality, they just mask the muddy appearance. Colorants are very useful in storm-water retention ponds. The water appearance is improved and the bottom is shaded. Muddy water is less objectionable.

Nuisance aquatic vegetation is one of the most troublesome pond problems. Control methods include: mechanical (pulling, cutting and raking); biological (fish that eat plants); and chemical (aquatic herbicides). We sell handheld cutters and rakes designed for controlling aquatic weeds. The problem is they require a lot of work and results are usually temporary. Biological control is usually the recommended long-term solution. Sterile grass carp and tilapia are effective but, require time. Chemical treatment is quick, but requires care. The type of vegetation must be identified correctly. Chemicals must be mixed and applied properly. Often special equipment is necessary for effective application. Improper chemical use kills many fish. We are licensed applicators of aquatic pesticides. We often spray nuisance aquatic vegetation for immediate control, apply a colorant to limit light penetration and inhibit new growth, and then stock grass carp for long-term control. New aquatic herbicides are available which are effective, relatively long-lasting and safe. Please contact us for more information.

Weeds along pond edges might be controlled by a winter draw-down of the water level to expose weed roots to freezing and drying. Lower the water level 3 - 4 feet in November and allow it to rise to normal in late Febnuary. (Winter draw-down may also help control bream overcrowding by forcing them out of shallow water where they are more susceptible to being eaten by predator fish.) Our winters haven't been cold enough for the last several years for draw-downs to kill vegetation.

Nuisance levels of pests should be controlled around a pond. Muskrat and beaver populations are exploding. Muskrats dig holes in the banks of a pond. These can weaken the dam or shoreline and present hazards when walking or mowing around ponds. Beavers cut down desirable trees and clog up drains. Eliminating brush and keeping pond shorelines mowed will limit habitat for these animals and make them more vulnerable to predators. Dogs patrolling the shoreline may help to limit muskrat and beaver populations. Usually the animals must be trapped and removed. Some people don't like the idea of killing these animals, but it is unfair and illegal to transport your pests to someone else's property. The most humane traps are those that quickly drown the animals. We have lists of trappers or you may contact your county extension service for names and phone numbers.

Mechanical methods are available to help limit animal damage in certain situations. Your pond shoreline can be lined with rock, gravel, sand or wire mesh to inhibit burrowing. During pond construction, a 6 - 8 foot wide shelf at the water level may deter muskrat burrowing. Covering valuable tree trunks with wire mesh, or split plastic pipe may prevent beaver gnawing. Pond standpipes cannot be clogged by beavers if you mount a section of larger diameter plastic pipe extending from about 6 feet below the surface to about 1 foot above the surface around the standpipe.

Turtles usually become nuisances only when they go after someone's bait when they are fishing. Snapping turtles may kill and eat young ducks. Slider turtles are much more likely to overpopulate. They sit on logs or on the bank sunning until disturbed, when they slide into the water. We trap turtles, remove them and we sell traps for both sliders and snappers. Sliders are caught when they climb a ramp to sun and drop off into a cage. Snappers are caught when they can't escape baited wire cages which are submerged.

The main problem snakes cause around ponds is scaring people. Nonpoisonous water snakes are by far the most common snakes around ponds. They look very much like cottonmouth water moccasins. As a result many more cottonmouths are reported than actually exist. Snakes help to keep other pests in balance.

Nevertheless, many people cannot possibly enjoy their ponds knowing a snake lives nearby. We catch and remove snakes with a snake catching pole having a wire noose at one end. Once again, keeping the shoreline brush controlled and grass mowed minimizes suitable habitat for snakes.

Ducks, swans and geese can become a nuisance if they overpopulate. Their droppings are messy. They can contribute to fish parasites. We have seen few problems when there are no more than about 8 ducks per acre of pond. Geese and particularly swans can become aggressive, particularly when nesting. Swans have occasionally prevented us from doing pond management activities. Waterfowl will also eat floating fish food intended for the fish.

Aeration and Fountains

Aeration devices are becoming popular for increasing the dissolved oxygen level in ponds. If food is available, oxygen is the next factor limiting productivity in ponds. Fountains, surface aerators, blowers, and paddlewheels enable the production of a pond to be increased dramatically. We can help you choose between oxygen production efficiency, appearance, cost and ease of maintenance. Timers and lights can be added to fountains. Surface agitation caused by fountains and aerators also helps prevent unattractive surface films of pollen, dust, tree litter, and algae. The splashing water sound is relaxing and muffles undesirable noises from vehicle traffic, neighbors or mechanical equipment.

Aeration choices for lakes and ponds

By: Johnny Foster; Foster Lake & Pond Management, Inc.

I've never seen a lake or pond that did not benefit enormously from aeration. In fact, aeration is the one expense hat can make the most improvement in the appearance and productivity of a lake or pond. However, property owners are confused about which type of aeration is most suitable and cost-effective for their situation. This summary provides some basics to help you decide which system you prefer. More detailed information will be provided in additional articles about specific systems.

Dissolved oxygen is critical for plant and animal respiration and problems develop when it is limited. Oxygen gets into lakes and ponds through diffusion of air at the water surface and from green plants, through photosynthesis. Diffusion at the water/air interface is greatly increased by moving water, ripples and splashing. Most oxygen supplied by plants comes from microscopic plankton, filamentous algae and submerged rooted plants growing in shallow water.

Lakes and ponds are depleted of oxygen in several ways. No oxygen is produced in water too deep for light penetration. Aquatic plants, including plankton, consume oxygen for respiration at night. Fish and all other aquatic animals are constantly "breathing" oxygen. Multitudes of bacteria probably consume the most oxygen as they digest organic matter such as dead leaves and tree litter, aquatic animal waste, chemicals and even other bacteria.

Another complicating factor is thermal stratification in lakes. Warm water is less dense than cold water and actually "floats" on top of cold water. Very little mixing occurs between layers and deep lake water is often very low in dissolved oxygen. Aquatic life is restricted to the upper few feet of water or it dies. Without oxygen at the bottom, toxic gases and excess nutrients are released that contribute to nuisance algae, odors and surface films. The entire lake is unattractive, unproductive and problems can be expensive to correct.

Aeration Methods

Many methods are being used to aerate lakes and ponds. A few of the most popular and most effective methods are described below. Most of our customers prefer: surface aerators, fountain aerators and compressed air supplied through diffusers. Aquaculture applications include: paddlewheel aerators, direct oxygen diffusers, surface aspirators and venturi air injectors. Other special applications require: pumped waterfalls, underwater circulators, air injected into deep "U" tubes, ozone injection and many other developing technologies. If you have an unusual situation, a different method might be applicable and we will be happy to discuss your options.

Surface aerators: These relatively efficient units use an electric motor suspended beneath a plastic float to push high volumes of lake water a short distance into the air where the water can absorb oxygen. Since the water is pushed only a foot or two into the air, the spray is not as attractive as a fountain. However, much greater volumes of water are circulated improving aeration. In addition to exposing large volumes of water to the air, they increase circulation (increasing oxygen diffusing from the air) and break down surface films. Ugly surface films caused by pollen, dust, algae, cyanobacteria, tree litter and insects are pushed to the shoreline by ripples and quickly sink. The splashing water muffles noise from traffic, neighbors or equipment. However, the spray pattern is not dramatic and "showy" and lights are not appropriate. These units are most often used in shallow lakes and ponds. Some units can be placed in water only 18 inches deep, but they are often used in lakes up to 8 feet deep. Some systems offer optional intake collars that pull deep water to the surface to reduce stratification. A basic one horsepower, double propeller unit that sprays roughly 1,000 gallons per minute 1 - 2 feet high will cost in the neighborhood of $1,000.00.

Fountain aerators: These are "hybrid" devices that provide much of the attractiveness of high-pressure fountains while still circulating large volumes of water through the air where oxygen is absorbed. Recent design improvements provide many spray patterns with high volumes of water being pushed by energy efficient motors with 3-year warranties. Lights add significantly to the cost, but are incredibly attractive. Colored lens are available for lights. Fountain aerators are used when dramatic attractiveness is desired in addition to surface aeration. Like surface aerators, the splashing water sound, surface film reduction and optional deep water intake collars add to their popularity. The general cost of a one-horsepower unit with crown & geyser spray pattern (9 feet high and 24 feet diameter pumping about 500 gallons per minute) without lights is somewhere around $3,500.00. Adding 4 lights would cost about $1,300.00 more. A steel control panel containing all GFCI breakers, timers and controllers is included.

Compressed air diffusers: These systems are incredible. They can provide up to 3 to 5 times more dissolved oxygen than other methods. A one horsepower motor can circulate 8,000 gallons of water per minute. A properly designed system can eliminate thermal stratification, reduce "muck" accumulation on the bottom, improve water clarity, improve fish production and reduce surface film. A one horsepower unit can aerate and destratify a 10-acre lake! The important factor is lake depth. Special "synergistic airlift diffusers" create rising columns of bubbles that expand as they rise through the water column. Each bubble gets larger and the column of bubbles spreads out pulling vast quantities of water up with them. Oxygen diffuses from the bubbles into the water and more air enters as the surface water is circulated. The surface boil of bubbles (only evidence of aeration in operation) may spread out as much as 100 feet. An on-shore compressor (in a fan-cooled cabinet) provides air to the diffusers via special plastic tubing. Although more efficient in deep water, smaller multiple diffuser units can be used in shallow water. Most systems we install cost $1,200.00 - 2,500.00.

Obviously, electricity must be provided for each of these aeration systems. Usually, a meter base or junction box needs to be provided near the shore of the lake or pond. Often motors up to one horsepower can use 120-volt supply. Larger units must have (and smaller units can use) 240-volt power supply. The cable must be sized according to the amperage of the motor and length of the cable. Ground fault protection must be provided because of the proximity of water.

These cost estimates are very rough. Desired options, motor size, cable length, choice of lights and the shape and depth of your lake or pond will determine your cost. Here are some questions you must be able to answer:

1. Prioritize your objectives. Rank the following in importance to you:
   a.) aeration efficiency
   b.) dramatic (showy) appearance
   c.) initial cost
   d.) destratifying
   e.) algae control
   f.) water quality improvement
   g.) muffling extraneous sounds
   h.) lights
   i.) operating cost
   j.) odor reduction
   k.) natural (discrete) appearance
2. Determine your power supply needs. Electricity needs to be supplied as close to the shoreline as possible. Do you have (or can you get) 120-volt supply or 240-volt supply or both. Would you prefer to supply an electrician or do you want us to supply one?
3. If you choose a fountain aerator, do you want lights? How many? What color?
4. How much electrical cable will you need? What is the distance from your existing, or anticipated, power supply to the location of the aeration unit motor?
5. Provide a rough sketch of your lake or pond showing shape, dimensions and depths.

Although somewhat complex, choosing an aeration system is by far the best thing you can do for your lake or pond. After installation water conditions will continue to improve each year. All of these systems are easily installed and we provide custom installation. Your lake will be much more attractive, more fish will grow faster and the life of the lake will be extended. You can easily pay for the aeration system with lowered maintenance costs year after year. Please don't hesitate to contact us if we can provide more information or answer your questions.

Conclusion

Private ponds are a tremendous resource to be valued highly. With a simple plan, a little study, some work and a commitment, a pond will be the center of many joy filled hours. We have the knowledge and the products to help. We welcome the opportunity to be of service. The complex biology of a pond is fascinating to most pond owners. As you manage your own little ecosystem, you will probably learn a lot and grow to enjoy the pond even more.