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How to Get Rid of Algae in a Pond (The Best Methods)

How to Get Rid of Algae in a Pond (The Best Methods)

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Algae growth in a pond is both natural and beneficial to your pond’s ecosystem, but too much can harm your fish and lead to unsightly green water.

Knowing how to get rid of algae in a pond is important to ensure the health and well-being of your fish. Natural methods such as planting aquatic plants and using barley hay are the most effective ways of controlling algae in a pond.

If you think there are a lot of algae in your pond, stick around as we’re about to cover the most effective ways to eliminate algae so you can keep your pond clean and beautiful.

Where Does Pond Algae Come From?

Algae is a common problem for pond owners, especially in the warmer months of the year. The warmer water temperatures in the summer can promote harmful algal blooms, which are the rapid and overabundant algae growth in a body of water.

These blooms occur when excessive nutrients, like nitrogen and phosphorus, are present in the water. The nutrients may come from various sources, like fertilizers, fish waste, or decomposing plant material in the pond. They act as fertilizer for algae, which leads to rapid algae growth.

When the algae population increases quickly in a pond, it can negatively impact the pond’s ecosystem. Oxygen levels may deplete and certain species of algae can release toxins that are harmful to humans and fish.

How to Get Rid of Algae in a Pond Naturally

Algae are normal and even beneficial for your pond. So, you don’t want to get rid of them completely. The best thing to do for your pond is to control algae growth with natural methods that are safe, effective, and environmentally friendly.

Remove by Hand

If you notice that the algae in your pond are getting too thick, one way of removing them is by using a skimmer or algae net to lift them out of the water. This method is especially effective with string algae.

It may be harder to scoop out blue-green or planktonic algae because they’re more dispersed in the water.

However, simply removing algae manually doesn’t address its root cause and it’s likely to regrow. You may even have to repeat this process several times in the summer.

As such, you should also use methods that focus on controlling algae growth.

Use Floating Plants

Floating plants, such as lilies, lotuses, water hyacinths, and water lettuces, can control algae growth by providing shade. The shade will reduce direct sunlight from hitting the water and keep the water temperature from getting too high, especially in the summer.

Warm water provides a more favorable condition for algae to grow, as it accelerates photosynthesis and increases the availability of nutrients. So, if the water can stay cool with the help of floating plants, it will limit the growth of algae.

Submerged Aquatic Plants

Submerged aquatic plants like Anacharis and Cabomba release oxygen in the water and compete with algae for nutrients.

When the water is oxygen-starved, microbes look for oxygen in the debris at the bottom of the pond. This process releases phosphorus into the water, which is food for algae and causes algae overgrowth.

Having plants that oxygenate the water and compete for nutrients helps starve algae and decrease their growth.

Use Barley Straw

Barley straw is becoming an increasingly popular method for naturally inhibiting algae growth. While it can’t kill existing algae, it can prevent new growth.

When exposed to sunlight and oxygen, barley straw produces a chemical that limits algae growth, but not the growth of aquatic plants.

The best time to apply barley straw in your pond is before algae emerge in your pond, around fall or early spring. If the water is cold, it may take 6-8 weeks for the straw to take effect.

In contrast, adding them to warm water above 70°F will make them effective in 1-2 weeks. To use them, loosely put the straw in cages or netting and anchor them to the bottom but allow them to float near the surface.

Use around two bales for every surface acre of the pond. Don’t overload your pond with barley as it can deoxygenate the water and harm your fish.

Increase Shading

Planting additional shade around the pond can also help control algae growth. Consider adding trees and ornamental plants near your pond.

Marginal plants like marsh marigolds will not only provide shade but also compete with algae for nutrients if you plant them in the pond’s periphery.

Will Vinegar Kill Pond Algae?

Yes, white vinegar can kill pond algae. However, you should use it with caution as it can affect the pH balance of the water and harm your fish.

Koi are especially prone to harm because their gills are sensitive to the acetic acid in vinegar.

If you plan to use white vinegar, don’t dump it in a filled pond. Even if you remove the fish, traces of the vinegar will still be in the water when the fishes are back.

The best way to use vinegar is by cleaning a drained pond with it. It can help remove stubborn algae stains and deposits.

If you only use small amounts, vinegar residue left after cleaning won’t harm fish and plants or disrupt the water’s pH balance.

Nonetheless, vinegar doesn’t address the root cause of algae and won’t be effective as a long-term solution. We still recommend natural methods for controlling algae.

Do Pond Fountains Help With Algae?

Yes, pond fountains can help control algae growth by aerating the water in your pond. The aeration process increases the oxygen levels in the water and reduces the nutrients algae need to thrive.

Increased oxygen helps aerobic bacteria thrive in the water. These bacteria then consume nitrogen and phosphorus, effectively starving algae and reducing their growth.

Apart from reducing these nutrients, aeration mixes warm surface water and cool water at the bottom of the pond. This process helps prevent stagnant water and thermal stratification, resulting in a healthier environment for fish and aquatic plants.

Can You Use Pool Algaecide in a Pond?

Pool algaecides shouldn’t be used in a pond because they contain chemicals that may be harmful to fish, plants, and other aquatic life.

Pool algaecides, which tend to be copper-based, contain chemicals that disrupt the cell walls of algae. This reaction has an oxidizing effect on the water, which can harm your fish.

If you do decide to use algaecide, it’s better to choose one that’s specifically designed for ponds. Pond-specific algaecides are safer for your fish and aquatic plants than pool algaecides.

Nonetheless, we recommend using algaecide as a last resort. Natural methods are still better long-term solutions for excessive algae growth.

Does Pond Salt Kill Algae?

Pond salt can be beneficial to your pond in safe quantities. It can improve your fish’s health and protect your pond from parasites and harmful bacteria.

It can also combat algae, but it’s not a recommended solution. Too much salt can harm freshwater plants, like water hyacinth and water lettuce.

The recommended amount of salt is one pound for every 100 gallons of water. You should remove any aquatic plants that are sensitive to salt and keep them in separate freshwater buckets when adding the salt.

You should also clean your pond before adding the salt and change at least 50% of the water. These preparations help the pond salt become more effective.

What Happens if There Are Too Many Algae In a Pond?

Too much algae growth in a pond can lead to a variety of problems. When left unchecked, these problems can eventually cause harm to fish and aquatic plants.

Here are some ways an algae bloom can negatively impact your pond.

Deplete Oxygen Levels

When there’s an overabundance of algae in the pond, they consume a large amount of oxygen. It creates an oxygen-starved environment where fish and other aquatic life will struggle to survive.

As the algae eventually die, bacteria and other microorganisms begin to break down the dead organic matter, further depleting the oxygen levels in the water. The lack of oxygen can lead to fish kills and other living organisms that depend on the pond’s environment to survive.

Cause Stagnant Water

Algae overgrowth can cause stagnant water in your pond due to depleted oxygen. In turn, stagnant water combined with sunlight increases the likelihood that toxic algae will thrive.

Stagnant water with a high amount of nutrients like nitrogen and phosphorus is a perfect breeding ground for blue-green algae that produce toxins. Toxins are also released when algae die off.

This toxic water can kill fish and aquatic plants. It can also harm pets and other animals that drink from it.

Toxins from the algae can even harm humans, as they can experience skin irritation when they come into contact with these toxins. They may also suffer gastrointestinal issues if they ingest the water.

Turn Your Pond into an Unsightly Mess

Algae growth can turn ponds into an unsightly mess. It can turn the water murky and discolored, making it difficult to see the bottom of the pond.

This murkiness can cause frustration, especially if you invested a lot of time and effort to create beautiful water features. Furthermore, algae overgrowth can create foul odors which can be unpleasant for you.

Can You Use Pond Algae as Fertilizer?

Yes, algae can be used as a fertilizer. Algae contain essential nutrients like nitrogen, potassium, and phosphorus, which help plants grow.

Apart from its high nutritional content, algae also have other benefits that make it ideal as a fertilizer. To start, because of its high nitrogen content, algae facilitates faster decomposition when mixed with compost.

Additionally, dried algae can act as soil humus. It promotes water retention and reduces soil loss during the rainy season.

Moreover, algae fertilizer is sustainable, renewable, and economical. They’re safer and more environmentally friendly than chemical fertilizers.

If you already have a pond that suffers from algae growth during the summer, you can harvest them and use them instead of throwing them away.

Final Thoughts

An algae infestation can be a nuisance to your pond. Luckily, there are many natural ways to get rid of it, from introducing aquatic plants to adding barley hay.

A natural approach isn’t only effective, but it’s also environmentally friendly. It helps you avoid the negative consequences of algae and maintain a healthy pond ecosystem where all aquatic life thrives.


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Kimberly Tourles

Tuesday 15th of August 2023

Thank you for this very informative article. We have a question that we hope you can help with. We have an upper pond that waterfalls into a lower pond. The upper is 1000sqft and the lower is 14,000sqft. This feeds a stone lined, shallow dug well adjacent to the lower pond. We have alot of algea in the upper and we would like to get rid of it. What would be safe for us to use? We have o fish but lots of frogs. The upper pond is not very deep but the lower pond is up to 13ft deep. Thank you so much!!!