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Why is Algae Bad for Ponds?
Friday, March 7, 2025
pond care
Why is Algae Bad for Ponds?
The term “algal bloom” probably registers as a bad thing to you. After all, it’s a known environmental hazard that can cause water safety issues. But what does this really entail for your pond? How does algae negatively affect ponds, and why is it a cause for concern?
At State Chemical, we manufacture and distribute chemical solutions for various purposes, including pond care. It can be easy to overlook random tasks like pond maintenance, but understanding the negative consequences of inaction is vital to avoiding them.
To help you understand what issues your pond may face, we will explain what causes algal blooms in ponds, the negative consequences of algal blooms, and how to approach an algae problem. After reading, you’ll know why algae overgrowth is an issue for your pond and how to treat it moving forward.
What Causes Algal Blooms in Ponds?
Algal blooms in ponds are caused by nitrogen and phosphorus, which drive the process known as eutrophication.
Eutrophication starts with pollution in the environment. Before pollution, water could naturally percolate and filter itself. Along the way, it would absorb nutrients that would end up in larger bodies of water. Now that we have pollution, however, water also absorbs pollutants and excess nutrients (namely phosphorus and nitrogen).
Once these nutrients end up in larger bodies of water (e.g., ponds), plant life flourishes—to an extreme degree. In particular, algae experience unfettered growth off the support of these nutrients, using up a lot of oxygen in the water and getting so out of hand that they block out sunlight in the pond. This is when algal blooms occur.
Through pond treatment, algal blooms can be kept in check, but if they’re allowed to continue their invasion, your pond can experience severely negative impacts.
The Negative Impact of Algal Blooms in Ponds
Algae growth doesn’t sound like it has to be a bad thing. After all, the idea of successful plant life probably sounds positive. Unfortunately, this overgrowth can be invasive—completely dominating all other life and leading to the deterioration of an entire ecosystem.
As previously stated, algae’s unfettered growth will suck up the pond’s oxygen and block out sunlight in the pond. This has implications for every other species in the pond ecosystem.
Without sufficient access to sunlight, other plant life dies off, adding to a decaying muck layer (also full of animal waste and other substances from runoff) in the pond. Forced to live in this rotting muck layer without sufficient access to oxygen or a food source, all the animal life will die along with the plants. Eventually, the algae will die too with the depletion of nutrients, and soon, the entire pond will be devoid of life.
This means the death of an entire ecosystem. Not only is this bad for local wildlife, but it’s not a good look for your facility. As time goes on, your pond will begin to appear gunky, green or brown, and full of debris that may even include dead animals. This is far from the welcoming, professional persona your facility wishes to portray, and it can be seriously off-putting to guests.
Let’s say you’re the head of grounds care for a hospital, which happens to have a pond. If visitors arrive and the first thing they see is a green, murky swamp, they’ll probably feel less confident in the hospital’s professionalism and ability to treat them. This really isn’t the first impression you want your facility to have.
This same concept applies to any property. Well-maintained grounds give visitors more confidence in your facility. This combined with the awful environmental impacts of algal blooms makes it crucial to treat algae in your pond.
How to Get Rid of Algae in Pond
To get rid of algae in ponds, you can use one of three types of pond treatment: dredging, chemical treatment, or biological treatment.
Dredging
Dredging involves the manual removal of algae and other debris from a pond using mechanical equipment.
This is a quick solution for debris removal when your pond needs it. However, it can still take days or weeks depending on the size of your pond, and with a cost range of $5,000–$100,000, it can be significantly higher priced than other treatment methods.
Plus, dredging is a reactive solution that can only be completed in response to eutrophication, meaning that this process will restart after dredging has been completed. That said, it can be an effective solution, especially in severe or time-sensitive situations, but it will not necessarily address the problem at its root.
Chemical Treatment
Meanwhile, chemical pond treatment involves keeping algal blooms under control by using chemical products to kill off algae and excess plant life.
This is a fast-acting solution. Within a matter of days, you’ll notice the breakdown of algae and debris, clearer water, and overall improved conditions. However, these chemicals don’t break down the phosphorus and nitrogen that are the root cause of the algal blooms.
Because of this, the algal blooms and other overgrowth will resume—and it could even come back worse due to the nutrients released when the chemicals kill off the plants. Additionally, in most cases, chemical pond treatment will kill aquatic life, including fish. For these reasons, chemicals can be a quick, effective solution when you’re in a pinch, but they are not recommended as a long-term solution.
Biological Treatment
On the other hand, biological pond treatment involves using a bacterial product to reduce excess nutrients through bioaugmentation.
Bioaugmentation is the process of cultivating a colony of bacteria to improve the health of the environment in which the colony is located. In ponds, this means adding “good” bacteria to outcompete “bad” bacteria for the same food sources. From there, the “bad” bacteria are starved out, and excess nutrients are broken down. This effectively removes excess nutrients from the ecosystem and reduces the negative effects the “bad” bacteria produce.
Through bioaugmentation, the “good” bacteria match their growth rate to the growth rate of the pollution. This growth then stabilizes in relation to the state of the pollution, and when the pollution declines, the “good” bacteria also decline. This way, the pollution is always kept proportionally under control.
Biological pond treatment is slower-acting than dredging and chemical pond treatment, with improvements usually not evident for at least a few weeks. However, while it is not a quick solution, it is a more effective long-term solution for algal blooms in ponds—plus, it’s more environmentally friendly.
Any of these treatment methods is an option for you based on your preferred approach toward pond treatment. As long as you keep your algae levels in check, “how” you treat the algae matters less than the fact that you’re treating it at all.
Learn More About Chemical vs. Biological Pond Treatment
Left unchecked, algae can create serious problems for your pond, the local ecosystem, and your property’s image. Now that you know why algae are a problem, read this article to learn more about chemical vs. biological pond treatment.
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