How to Control Algae in a Large Pond


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Algae blooms are by far some of the most harmful infestations your ponds, be they large or small, can suffer. If you have an algae problem, you might have seen that clear waters can end up infested in a matter of days by algae growth.

Not only are algae extremely hard to remove, but they can obstruct pumps, affect wildlife, harm beneficial bacteria, and release toxins. This leads to an overall decrease in the quality of the water in your pond both short and long-term. Fortunately, algae control can fix most of these infestations.

In this article, you will learn what are the dangers of letting pond algae run amok in your large pond. We will also look into the best way to control algae in your pond. And without using any chemicals that may decrease the quality of your pond water!

Why are algae bad for your pond?

Algae are microscopic aquatic organisms. They can carry photosynthesis, which makes sun and nutrients into living matter and can grow fast. They can fill out big volumes of water if enough sunlight and nutrients are provided. Algae growth is dependent on nutrients. Algae blooms take place if the water of your pond is rich in nutrients and sunlight. Algae are like plants in that they are diverse, and many species exist. Different species can lead to different kinds of algae growth in pond water.

  1. Green water is made from millions of individual algae cells. These cells can avoid most filters and quickly fill ponds. Known as planktonic algae, you won’t be able to manually remove them.
  2. Hair algae form narrow and intricate filaments and rely on high light levels.
  3. String algae form thick mats on the surface. They can grow extremely fast and deplete the oxygen of your pond.
  4. Blue-green algae are surprisingly not pond algae at all, but cyanobacteria! Cyanobacteria can be considered the earliest and most primitive ancestors of algae. Even though they are much simpler, they are not less harmful. These microorganisms thrive in sunny, calm waters. The algae blooms they form are blue and green. Blue-green algae are the most likely to produce dangerous toxins.

Although algae are present in almost all aquatic environments, their uncontrolled growth is what puts your pond at risk. Algae blooms can end all life in a pond, from fish to plants like water lilies and beneficial bacteria. Sometimes, they even make the water undrinkable! Algae can consume oxygen directly, through respiration during the night, or indirectly. Night respiration can remove some oxygen, which can kill some animals. However, when the presence of algae in a pond becomes too high, some begin to die and fall to the bottom. There, they are decomposed. This decomposition can quickly deplete all the oxygen in the pond and render it lifeless. This situation should be avoided at all costs. Even pond aeration can’t supply enough oxygen in these extreme cases. Even though algae aren’t always bad, those reading this article will likely want to find out how to reduce algae or even get rid of them.

How to control algae in a large pond?

Large pond algae control is a complex matter. Most methods that can kill algae can also affect wildlife, fish, and overall water quality. Some recent approaches can be as successful as previous ones while reducing the amount of chemicals and their toxicity.

  1. Chemical algae control uses chemicals called algaecides (algae-killers), which stop algae from properly functioning. The dead pond algae can then be joined together and removed after they drop to the bottom. These water treatments are effective for green water algae. Still, adding chemicals to pond water negatively affects any wildlife inhabiting it. Because of this, safer options have been developed.
  2. UV light algae control takes advantage of the destructive power of ultraviolet light. Its main problem is that UV light is harmful to most living beings. This includes humans and any wildlife inhabiting the pond. To limit its effect on algae, irradiation takes place in a small bulb with an opaque covering. Pond water is filtered through it, and any small algae cells that enter it are quickly killed. The main limitation of this approach is that only very small algae can be removed through UV light.
  3. Ultrasonic algae control uses a totally safe technology that precisely targets blue-green algae. By using low-energy ultrasounds, a process called cavitation is induced inside the vesicles of blue-green algae. This leads to their death and can reduce algae levels by almost 100%. Ultrasounds can travel very fast through your pond and disrupt algae while leaving the rest of the ecosystem untouched. This makes it completely pet safe. Ultrasonic algae control is the go-to choice when seeking to efficiently control blue-green algae. It provides safe and natural algae control for ponds. New sonic solutions for algae control can replace older and less natural methods as a long-term solution.
  4. Manual control is a cheap but intense alternative. It is very useful for algae that form densely packed structures, such as string and hair algae. In these cases, removing the algae masses manually can be easier than subjecting the pond to the chemicals required to kill them.

Barley straw is another commonly used algae control method, but its efficacy is quite controversial. It is said to prevent algae from growing through its decay, but no strong proof has been found of this. Although there is no harm in using it as an addition, you should not rely on it to control the algae of your large pond.

How to Get Rid of Algae in a Large Pond Without Harming Fish?

Algae and fish don’t mix well, as pond algae blooms can easily kill most fish in a large pond. Many algae control methods can also have negative effects on fish. Due to this, fish and pet-safe algae control for ponds is something many people want. Most chemical algicides can be toxic for fish, which is why they should be avoided. UV and ultrasonic algae control can be helpful in reducing algae levels while leaving fish safe and sound. UV-light pumps can be ineffective in large ponds. In these cases, ultrasound alternatives offer pond algae control safe for fish.

What is The Best Algae Killer for Large Ponds?

There is no single best algae killer or best algae control for ponds out there. Thankfully, depending on your situation and that of your pond, some approaches can lead to much better results than others. Algicides are useful on extreme algae blooms but will greatly affect the wildlife of the pond. UV-light control can quickly destroy green water, but it is less useful in large ponds. Finally, ultrasonic algae control has great potential, especially when treating blue-green algae in moderate climates. It is also less invasive than other options and leaves wildlife and fish unaffected. This makes it the safest and least work-intensive option for large ponds and fisheries.

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