How to Get Rid of Algae in A Large Pond

By Algal Web

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Ponds can lose their beauty when these green organisms appear. Algae are inevitable for some reasons, and when they overtake the pond, it can be tasking to get rid of them. 

When you leave them to populate your large pond, you should get ready for real work to get rid of them, depending on how much of it lives there. Are you ready to remove those oxygen-depriving algae from your large pond? The perfect solutions await you in the article. 

Read on!

Causes of Algae Growth

Knowing the root causes of algae growth in ponds will help you combat it better. What’s more? It can help you prevent future occurrences. In case you haven’t noticed or didn’t know, here are some of the reasons pond algae appear:

1. Fish and food waste

Fish and food waste can cause algae bloom and growth in a pond. The waste, when it stays too long in the water, begins to decay and cause a breeding ground for algae.

2. Excess nutrients

Excess nutrients from food, supplements, phosphorus, and nitrogen can cause algae to appear in ponds. Generally, algae feed on nutrients, which are usually abundant when there’s an excess. They can take over your pond and keep returning unless you cut that source.

3. Fertilizer

Using fertilizers in your pond is an open invitation for algae growth. Of course, there are times you will need to use fertilizers for some aquatic life in your pond; however, it can be detrimental when there’s excess. Fertilizer is a free ticket to getting enough nutrients from your pond.

4. Light exposure 

Light exposure can cause algae growth. The presence of light exposure is an avenue for algae to appear. Sunlight helps with photosynthesis, which aids their rapid growth.

5. Water movement

Your pond’s water movement or absence of it can make algae appear. For example, filamentous algae usually appear in ponds with shallow water. 

Low dissolved oxygen will lead to phosphate release into the pond and encourage algae growth. Plus, algae-like water movement in ponds.

6. New ponds

When your pond is new, it’s prone to algae growth. This is because the water is new, and nutrients are released from the source. 

Another cause is that as you add plants and other things to the pond, the water gets nutrients and will be disturbed, which are comfort zones for algae. However, you can take some measures to prevent algae from growing in your pond, which you’ll find out later in the article.

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How Many Algae is Too Much in A Pond?

Little algae in your pond might not be at the worst stage yet, but it’s nothing to joke about. Algae become worrisome when it covers more than 20% of the water surface in your pond. You shouldn’t wait till it escalates to this level before you do something.

The more algae growth, it can cause stagnancy in the water and be detrimental to your fish and pond plants. Therefore, you should remove algae immediately after they appear.

Why Remove Algae From Ponds

Small algae are no cause for alarm. In fact, algae can be good; however, they can be catastrophic as well. Here’s what happens when you leave algae for too long in your pond:

  • Taste and odor problems in the water, ruining fish food and filling the atmosphere with unbearable odor.
  • Algae can release toxins that are harmful to fish.
  • They deprive fish of oxygen and nutrients, release toxins, and all these can kill your fish.
  • Algae causes changes in watercolor.

How to Get Rid of Algae in A Large Pond?

Algae can mat over your pond surface, appear hair-like, have dots on the walls, or as green water. When you notice these, you need to take proactive actions in removing algae before they cause harm to your fish.

Here are some solutions:

1. Pond aeration

Improving your pond aeration is an effective way of reducing and getting rid of algae. Aerating the pond will improve water quality, circulation, and oxygen levels. 

As a result, there will be less sludge in the water, making it clearer. This will create a more balanced ecosystem in the pond and the aquatic life, kicking the algae out.

However, choosing which aeration system can be challenging depending on the size of your pond. The bigger and deep your pond is, the more powerful the aeration system you need. 

Here are some suggestions for you:

2. Pond dye

Applying pond dye can help stunt algae growth. Pond dye will change the pond water, clouding it and preventing algae from getting enough sunlight needed for growth. This is a nice preventive method if you add it enough before algae show up. 

You’ll have to clean up dead algae from your pond after using pond dye to remove them before they decay. Some good pond dyes include:

3. Barley straws

Another way to get rid of algae in a large pond is by adding barley straws to the water. You need to get some barley straws and place them where you notice algae growth. Barley straws release hydrogen peroxide into the water, slowly and effectively killing off algae.

You can use a recommended measurement to know which amount of barley straws is right for your pond without harming your fish. For example, 8 ounces of barley straws is good for 1,000 gallons of water. After some weeks, the algae will die off, and you can remove the barley straws.

However, you should be careful when using them. You shouldn’t add too much and don’t leave them for too long in your pond if you don’t want the effects to get to your fish or plants.

4. Algae eater

A quick, effective, and natural way to eliminate algae in a large pond is to introduce algae eaters into the water. Their job will be to feed on the algae and prevent them from growing. Algae eaters like fish, shrimp, and snails are essential for controlling and removing algae.

Algae-eating fish like plecos, twig catfish, otocinclus catfish, and others are great for ponds. However, before adding them to the pond, ensure they’re compatible with other fish in the water, the temperature, pH level, pond size, and the general ecosystem. Then, you can add nerite snails, Ramshorn snails, or Amano shrimp in the pond.

5. Balance the water ecosystem

Balancing the ecosystem in the pond will help get rid of algae. This involves keeping the temperature, pH, and water level at the required level. Furthermore, you’ll need to filter out excess nutrients from the water to starve algae. 

6. Pond plants

Adding plants to your pond can help kill off algae. The plants will absorb the nutrients in the water and deprive algae of any. 

Getting floating plants is beneficial because they can shade the water and prevent sunlight from reaching algae. Submerged plants are also great because they use nutrients in the water. Some life pond plants to add are:

7. UV clarifiers

UV clarifiers have ultraviolet lights that kill off algae in ponds. Investing in good UV clarifiers can have you saying goodbye to persistent algae growth. A good UV clarifier will destroy algae between three to five days. 

The downside to UV clarifiers is that they can also kill beneficial bacteria in your pond. Some good UV clarifiers are:

8. Treat with algaecide

You can also get rid of algae by using algaecide in the pond. This method is effective between three to ten days after the first treatment. 

However, they may contain chemicals that can harm life in the water. Therefore, algaecide should be your last resort after trying other methods, and algae persist.

9. Remove early blooms

Removing early algae blooms from your pond will prevent them from taking over your pond. If you notice green slimes or dots on the walls, remove them with nets, rakes, or hands, or brush them off. You should catch them when they’re still little. 

How to Remove Pond Algae Without Killing Fish

Naturally, removing algae is the safest way to get rid of them without killing your fish. Of course, other methods are safe, but not as much as the former. 

Generally, you can protect your fish while removing pond algae by removing them manually, introducing algae eaters into the water, and adding pond plants.

Other safe methods are adding pond dye to the water, using UV clarifiers, boosting the aeration, and using an effective filtration system.

Preventing Algae From A Large Pond

Algae are common in large ponds, but you can prepare ahead and prevent them from taking over your pond. Here are some actions to take:

  • Add pond dye to the water early enough to deprive algae of photosynthesis.
  • Ensure you clean your pond’s filtration system occasionally.
  • Refrain from overfeeding your fish, and remove leftovers immediately.
  • Provide and ensure proper aeration in the pond.
  • Create shade for your pond, like shade mats, to limit sunlight. Don’t rely on large trees because fallen leaves can decay in the water and invite algae.
  • Add a border or a rim around your pond to prevent overflow of nutrient-filled water from around it.
  • Stock your pond with algae eaters.


No one invites algae purposefully into their ponds; however, they appear when the condition in the pond is favorable to them. Ensure you employ the most natural ways possible to eliminate algae before resorting to other methods if there are no changes.

Furthermore, ensure you invest in a quality aeration and filtration system to balance the pond’s ecosystem and prevent algae from growing.

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