What is Algae in Ponds?

Algae in ponds is often a catch-all for all aquatic plants and aquatic plant related problems. this page separates the two for this reason. Not all aquatic plants are algae in ponds. Also, not all algae is created equal when it comes to how desirable or undesirable it is in your pond.

Part of the reason many call all aquatic plants algae is because even experts differ on what to call or classify algae. Defining algae in ponds is very difficult, but basically, algae is a simple organism that can be composed of one cell or many cells grouped together in a colony. There are three basic types of algae in ponds, planktonic, filamentous, and attached or erect forms.

Planktonic algae in ponds are single-celled, microscopic plants which are distributed worldwide. Blooms can be bright green, pea soup looking or even a blood red color. They are the base of the food chain and a healthy existing pond or well prepped new pond must have planktonic algae as a food source.

Filamentous algae in ponds are called many things such as pond scum or moss, and they are typically found at the surface in the form of greenish mats. Typical growth begins on the edges of ponds and will slowly rise until it arrives at the surface. This series of cells joined together has a slimy, cottony or course texture. It can look like the stringy masses covering the Algae Monster at the top of the page or it can be “scum” as in the picture to the left. Filamentous algae will grow in ponds with higher levels of calcium and phosphorus. It is common to have this type of algae encouraged after ponds are limed to enhance fish production. Filamentous algae in ponds typically are of little or no value to ponds.

Attached-erect algae in ponds are non-rooted but dense. A misconception is that it looks like a higher vascular plant, which causes a lot of confusion. It typically has a gritty and bristly texture and is not much use to the overall pond health.

Blue-Green algae in ponds is often the biggest culprit when it comes to “pond scum” problems. Recently, it has been reclassified in the Monera Kingdom which consists of bacteria instead of being classified with other types of algae because the blue-green algae in ponds relates more closely to bacteria than other forms of algae. Within the blue-green algae grouping, there can be several varieties that can have many different colors such as red, brown, or yellow. Blue-green algae are nitrogen-fixing organisms and only need nitrogen and carbon dioxide to live, both very prevalent in most ponds. When there is a blue-green algae bloom, it forms dense masses on the surface of the pond and can cover the entire body of water. In fact, it is believed that the Red Sea was given its name from a red species bloom of blue-green algae.

Benefits of Algae in ponds

Algae in ponds, in general, serve a purpose and are essential for a healthy pond. Planktonic algae is the first link in most food chains that occur in your pond and your pond ecosystem needs algae. Zooplankton feed on planktonic algae and bait fish and fingerling sport fish in turn feed on the zooplankton. Without a food source, the bait fish and fingerlings will struggle and not thrive in your pond. Often times, pond owners who are managing their pond for trophy bass production will fertilize their ponds to keep the planktonic algae population very high. This serves to provide more food for zooplankton, bait fish and fingerlings and also blocks much of the sunlight from reaching the bottom of the pond. In turn, other aquatic plants struggle which decreases the areas for bait fish to hide and gives the bass a much easier meal to come by.

Problems with Algae in Ponds

Often the most frequent complaint about algae in ponds is aesthetics. A green pond covered with algae is unsightly and is an eye sore. The enjoyment of the pond or water feature is diminished when algae has taken over.

Algae poses a problem to your pond health when you have too much algae and during algae blooms. During the photosynthesis process when plants use sunlight and carbon dioxide to produce food, they give off oxygen. Photosynthesis is a good process for your pond. The plants are using carbon dioxide and giving off oxygen which is needed for your fish, the decomposition of organic matter, and other processes within your pond. However, photosynthesis only occurs when there is sunlight. As the sun goes down, plants turn from oxygen producing organisms to oxygen consuming organisms. Therefore, the more aquatic plants and algae you have in the pond or body of water, the more oxygen they will give off during the day and the more they will consume during the nighttime hours. As the night goes on, the oxygen levels continue to decrease. The lowest levels of oxygen will be just before sunlight in the morning before the algae and plants start producing oxygen again. If your pond has too much plant life, the oxygen levels can decrease to the point that large fish struggle to live.

An algae bloom is a rapid reproduction and spreading of algae in ponds when conditions are right. Algae blooms typically occur during the hot, sunny, calm part of the summer. When an algae bloom occurs, your pond can be covered with algae in a very short period of time. The major problem with an algae bloom is the algae in ponds die off. Often even quicker than the bloom itself, the algae die off can create major problems. A die off of an algae bloom can be caused by a cloudy day and lack of sunlight, a cold front, storms, etc.

When the algae bloom dies off, it adds a large amount of dead organic matter to your pond. This organic matter is decomposed by microorganisms at the pond bottom. With the added organic matter load on the pond, the total amount of decomposition occurring in the pond increases and the decomposition process uses up oxygen and gives off carbon dioxide.

This causes two problems. The first is lack of oxygen. When the oxygen in the pond is used to decompose the dead algae in ponds, it is not available for fish and other aquatic life. A die off can be so severe that most of the available oxygen in a pond can be used up in the decomposition process and your fish and other aquatic life will start to die off. The larger the organism, the more oxygen it uses. Therefore, your larger fish that have been in your pond for several years will be the first to die when oxygen is taken up.

The second problem with a large die off and increased organic matter is nutrients. When the algae in ponds die off and are decomposed the carbon dioxide and nutrients are released back into the pond and is available for the next generation of plant material. The carbon dioxide and nutrients help to begin the cycle all over again.

Excessive algae in ponds growth will also limit sunlight from penetrating the pond and can cause significant thermal stratification, which is temperature layers throughout the pond. The water that does not receive the sunlight and warmth cools and becomes more dense. This dense water sinks and oxygen levels decrease because it is not in contact with the air. It can also cause turnover in fall and spring.

Another problem with excessive algae in ponds growth is irrigation problems. Many golf courses, farmers, and home owners use ponds as a holding area for irrigation water. If the pond has excessive algae growth and is pumped for irrigation purposes, the algae in ponds can clog the pump and filters within the pump, adding many hours of labor to the project. The algae that passes through the pump will be distributed throughout the lawn or area irrigated and can be unsightly when it dies off, as well.

How Aeration Can Help

There is hope for backyard pond, though. Aeration can protect most pond and fish during an algae in ponds bloom and die off. Adding an aeration device, such as an Aerating Fountain will provide added oxygen to the water and help buffer the effect of an algae die off. When the algae in ponds die and are being decomposed, the added oxygen allows the decomposition process to occur properly and also provide oxygen for the fish and other aquatic organisms. By splashing the water in the air, the aeration device is not only adding valuable oxygen, it is also helping to vent gases such as carbon dioxide which is being produced in large amounts from the decomposition process.

Using a Pond Aerator or Aerating Fountain will also help prevent an algae in ponds bloom in the first place if it is installed before there is a major problem. As discussed above, the added oxygen will help the decomposition process and actually make that process occur quicker. It will also vent the extra carbon dioxide. This means there will be less available for the algae in ponds to use, which is one of the key components to blue-green algae problems.

Adding an Aerating Fountain, or Water Circulator will also create surface agitation in the pond or body of water. This is beneficial in a few ways. First, it helps eliminate the still stagnant water areas and mimics natural wind. As stated above, algae in ponds and algae blooms typically occur in the hot, calm, sunny times of the year. The agitation at the surface that eliminates the stagnant areas decreases the areas algae have available to them to thrive. Just simple movement of the water will help limit the amount of algae present in the pond.  Algae do not like moving water or surface agitation.

Surface agitation is also beneficial because it helps to mix up the algae that is already present within the water column. Algae is not able to sit at the surface of the water and soak up all the sunlight it needs for photosynthesis and it cannot survive without large amounts of sunlight. The agitation also helps to destratify the pond by mixing up the water and limiting the negative effects of turnover. With water that has been thermally destratified, the pond is now more hospitable for desired plants and algae species and creates a better pond ecosystem.

Aeration can cause a shift in the carbon dioxide levels within the pond and, in turn, can shift the pH levels causing conditions that are more favorable for desirable algae to out compete the undesirable blue green algae.

Finally, the agitation helps refract some of the sunlight that hits the surface of the water. This limits the amount of sunlight that can penetrate the water column. With less sunlight throughout the water column, algae and other aquatic plants struggle to survive. Some will still linger, but it will help limit the overpopulation of algae and other aquatic plants.

Aeration should not be viewed as a panacea, or silver bullet, but more as one of the many tools typically used in combination with other methods of algae control. Added aeration can never hurt a pond (unless start up of an aerator causes turnover) and most of the time there will be some type of water quality benefit of added oxygen, not to mention the increased oxygen levels are great for pond fish.

Florida Pond Management is you expert organization in the business.  Have a stagnant pond or lake problem?  One call can set you on the way to a healthier pond or lake.

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Florida Pond Management

817 Appleton Avenue

Orlando, Florida 32806

Phone: 407-472-9258

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