Algae are simple photosynthetic organisms and can exist as single celled organisms, or form filaments or colonies. Algae are the base of the food chain and their presence is necessary to a healthy lake or pond ecosystem. Excessive algae growth however, is the number one problem faced by pond owners. Excessive algae growth is referred to as an "algae bloom." A Planktonic algae bloom is a proliferation of the single-celled form. In extreme cases a Planktonic bloom will take on the color and consistency of pea soup. A filamentous algae bloom can occur as stringy, moss-like mats that cover the bottom or float at the surface of the pond. Colonial blooms are typically blue-green algae. They occur as gelatinous mats or globs that are green, brown or black, and may cause noxious odors. An algae bloom in a lake or pond is a sign of an unbalanced ecosystem. The usual cause is excessive nutrient inputs.
Algae can be controlled with algaecides. Algaecides are important tools for pond management; however they are a temporary fix. A sustainable, long-term approach to pond management involves controlling and managing nutrient inputs. Avoiding the use of lawn fertilizers and maintaining buffer strips of un-mowed vegetation around your lake or pond are ways to reduce nutrient inputs. Most professional lake and pond managers use biological products, such as Beneficial Bacteria and enzymes to limit the availability of nutrients within a pond. The cultured bacteria that are applied to ponds are invisible organisms that compete with algae for nutrients. Products that reduce phosphorous are also commonly used in pond management. These may include polymers or alum products that physically bind to phosphorus, making it unusable for algae growth.
Algae can also be managed or controlled by physical means, such as mixing aeration systems. Complete mixing, or de-stratification, of a pond can eliminate the stagnant conditions that cause algae to thrive. Application of dyes or colorants to the pond water is another physical control method. By darkening the water to eliminate UV light, algae is starved of the sunlight it needs to live.
Nuisance Aquatic Plants
Aquatic plants can provide considerable value to a lake or pond. They stabilize bottom sediments. They provide important habitat for fish. They provide food for waterfowl. They also tie up nutrients that might otherwise contribute to algae blooms. Therefore it is not a good idea to remove all aquatic plants from a lake or pond. When dealing with native aquatic plants, it is best to limit your control efforts to high-use areas, such as swimming beaches, boat mooring areas and navigation lanes. Granular herbicides can produce localized control and are well suited for this kind of treatment. Weed cutters and rakes are other tools that can provide localized control.
In pond environments, weed growth can often be limited by the application of dyes and colorants, (see our Midnight Blue Organic colorant). These products physically block sunlight UV rays, thereby limiting submerged plant growth to shallower areas of the pond. By managing aquatic plants in this manner, fish habitat is provided in the shallows, while boating and angling uses are maintained in the deeper portions of the pond.
Duckweed and watermeal are species of free-floating aquatic plants that can form a dense green mat that covers the surface of ponds and protected areas of lakes, such as bays, lagoons and boat channels. Herbicides for controlling these plants can be found in our article on chemical week control. Since these plants thrive in stagnant conditions, their growth can often be inhibited with aeration or Water Circulators.
It has been the experience of our Pro Staff that most complaints about nuisance aquatic plants are due to invasive exotic species, such as Eurasian water Milfoil, curly-leaf pond weed, and Hydrilla. These invaders have few natural controls. Thus they tend to reach very high densities. When dealing with invasive exotics, it may be best to try to selectively treat them wherever they are found. Certain herbicides will target exotic plants while having few impacts on desirable native plants. Herbicides for controlling these plants can be found in our Chemical Weed Control article.
Nuisance Shoreline Plants
As with aquatic plants, shoreline and emergent plants provide many important values for lakes and ponds. They prevent shoreline erosion, capture runoff and provide important habitat for fish and wildlife. In natural lakes it is best to limit removal of native shoreline vegetation to the minimum required for access. In ponds, control of shoreline vegetation may be more critical. Certain species, such as cattails and willow brush, may completely choke out a pond if not controlled. Roots from trees and brush may also damage dikes and dams if not controlled.
Only herbicides labeled for aquatic use should be used along shorelines. The herbicides that control weeds in your driveway and lawn may also kill weeds along your shore, but you should not use them unless they have an aquatic label. Even if the active ingredient is the same, non-aquatic herbicides may contain adjuvants that are harmful to aquatic life. For a listing of herbicides that are labeled for aquatic use and will control most common weeds as well as woody growth, refer to our article on Chemical Weed Control. Many of these herbicides bio-degrade very rapidly upon contact with soil or water.
Sediment (Muck) Accumulation
Sediment that accumulates on the bottoms of lakes and ponds is either organic or inorganic (mineral). Inorganic sources include sand and soil blown in by wind or washed in by rain. Organic sources are decaying leaves, aquatic plants, algae, and fish and animal waste. Inorganic sediment accumulation may be controlled by maintaining buffer strips of un-mowed vegetation around the shoreline. Organic sediment accumulation is the more common problem for ponds. Organic sediment tends to be dark brown or black and often has visible bits of plant matter in it. Laboratory analysis can determine the exact composition of your sediment.
Organic sediment accumulation is very problematic in ponds because ponds are more prone to oxygen depletion in the depths. Under anaerobic (without oxygen) conditions, organic matter decomposes very slowly. By installing an aeration system you can create an aerobic environment that greatly accelerates decomposition of organic sediment. Sediment decomposition can be further accelerated in ponds through the application of Bacteria & Enzymes. Pellet-type bacteria products are formulated to specifically target pond and lakebed sediments. Many lakefront property owners have reported good success using bacteria pellets to remove organic sediments from there lakefront swimming areas as well.
Fish kills may be caused by temperature stress or by toxic blue-green algae blooms. But most fish kills are attributable to low oxygen levels. In pond environments, fish kills become more likely as ponds age, because ponds become more fertile. Increased fertility results in increased plant and algae growth, and therefore increased amounts of decomposing organic matter. Organic decomposition is the primary cause of oxygen depletion in ponds. Installing Aeration Systems can reduce the likelihood of recurring fish kills, but the best approach is to aerate your pond along with managing nutrient inputs and sediment accumulation by using Bacteria & Enzyme products such as our Clear Pond Sludge Remover and clarifier with Bacteria and Enzymes.
Poor Water Clarity
Poor water clarity is the result of materials suspended in the water column. Murkiness can be caused by wind and wave action, erosion and surface runoff. Suspension of materials in the water may also be caused by burrowing muskrats, feeding ducks or by fish, such as bullheads and catfish that root around on the bottom. Planktonic algae blooms will also cause poor water clarity. Identifying the causes of poor water clarity is the first step in remedying the problem. When the causes cannot be directly dealt with, there are management options for directly controlling suspended matter. If the suspended material is predominantly organic in nature, the use of Aeration Systems along with Bacteria & Enzyme treatments will allow the suspended material to be consumed. Bacteria and enzyme formulations labeled for “water clarity” or “water quality” are usually best suited for this application. If the suspended matter is predominantly mineral in nature, then Phosphorus Removal products, such as polymer and alum products, will bind to suspended particles and cause them to settle out. (See our Crystal Lagoon product)
Many biting insect species associated with lakes and ponds have aquatic life stages. These include mosquitoes, black flies and no-see-ums. However, these insects may not originate from your lake or pond if it is well-stocked with fish. Fish do an excellent job of keeping biting insect larvae under control! These biting insects may begin their life cycle in isolated patches of water such as puddles, ditches, even old tires full of rain water. You can achieve good control of biting insect larvae by treating these areas with Mosquito Dunks, a bacterial pathogen that is harmless to humans, fish and animals.
If your pond does not contain fish, you can also control biting insects by installing Fountains, which produce a high level of turbulence to control biting insect larvae.
Ice and Debris Problems
Ice can damage boats, docks and shorelines. Water aerators, Circulators or De-Icers are products designed to reduce or eliminate damage caused by ice. These operate by drawing warmer water from the bottom of the lake or pond and circulating it near the surface to melt the ice. These same devices can also be effective in keeping channels and boat slips free of floating weeds and debris.