How to get rid of algae in large farm ponds

One day you decide to walk over to your farm pond to soak in the scenery. But once you reach it, you’re assaulted by the sight of disgusting green sludge. The foul stench doesn’t improve your mood either. Algae have taken over your pond. Should you be worried?

While every pond contains at least a few algae, large numbers can often become a problem. To protect your pond’s ecosystem, you should know how to deal with this aquatic menace. This article will tell you everything you need to know about algae control in large farm ponds. You’ll learn how to treat, kill, and prevent it.


We tested various products and found the best way to control algae in large farm ponds, treat, & kill it by using API Pond Algaefix. The best value-for-money algae remover and runner-up for large farm ponds was Spaces Places.

In this article, we cover various things including the following:

  • Preventing algae in the first place
  • Maintenance
Algaecide For Waterfalls, Ponds

Table of Contents

How to get rid of algae in a large farm pond

Getting rid of them is easy once you get the tools you need. This simple guide will teach you everything you need to know about the removal process:

How to get rid of algae in a large pond

  1. Invest in a rake or a skimmer.


  2. Manually remove as much of the bloom as you can.

  3. Consider which algaecide you want to use.

    We recommend the ones on the list below.Pond & Fountain Algaecide

  4. Read the instructions on how to use the algaecide and apply it.

  5. Check the state of your pond each day. Continue using the algaecide as needed.

  6. Once you’ve cleared the bond, take as many preventative measures as possible.

    You can find some of our tips in the next section of this article.

  7. Practice good maintenance habits to keep the ecosystem stable.


How to prevent it

The best way to keep these aquatic lifeforms in check is prevention. Even if you use an algaecide successfully, it doesn’t mean the issue won’t return later. If you apply the following 3 preventative measures, you’ll keep the risk of regrowth to a minimum.

Build your farm pond properly

Though many people build their ponds with a steady shoreline gradient, this encourages algae growth. Ideally, your shoreline should be at least 2 to 3 feet deep.

It limits the amount of sunlight that reaches the bottom. Insufficient sunlight restricts photosynthesis and prevents unwanted growth.

Cover it with a protective trap

Changing the shoreline gradient isn’t an option if you’ve already built your pond. But that doesn’t mean you’re helpless.

You can cover the floor with plastic sheets and secure them with stakes. Before using the sheet, create holes to allow oxygen to pass through.

Introduce the right fish that eat it

Certain fish eat algae as part of their natural diet. The Asian grass carp is the perfect example of such a fish. You should introduce between 5 to 15 fish per acre, depending on the scale of the growth.

3 best algae removers

Prevention is the best medicine. But once the algae get out of control, you won’t be able to handle them without a good algae remover.

We recommend the following three products:

Best overall

This algaecide will eradicate every sign of algae in your pond. It’s highly selective, so you don’t have to worry about your plants and fish. It has a very simple instruction manual, making it great for beginners.

Country of OriginUSA
Item Weight2.18 pounds
ManufacturerMars Fishcare
Product Dimensions3 x 4.5 x 7.5 inches


  • It’s great value for the amount you pay.
  • You can follow their chart to see how much product you need.
  • It’s safe for fish.


  • You’ll have a relatively large container standing around.
Get it for your pond.

Best cheap remover

This option is great for ponds and fountains alike. In addition to killing algae, it also clears the water. However, it’s not a good option if you have fish.

NameEasyCare FounTec Algaecide
Brand Name‎EasyCare
Item Dimensions LxWxH‎2 x 2 x 6 inches
Package Weight‎0.27 Kilograms


  • It also works on a rock fountain.
  • It’s a trusted provider with thousands of happy customers.
  • A fountain installer recommended this to us.


  • It may take more solution to get the job done than the manufacturer says.
  • It could make it less affordable.
  • It’s not safe for fish.

Best value-for-money remover

Our final remover is both cheap and effective. It’s safe for aquatic life and won’t disrupt the pH. Its only downside is the size.

NameSpaces Places
Country of OriginChina
Item Weight1 pounds
ManufacturerBeckett Corporation
Product Dimensions2.8 x 2.8 x 7.5 inches


  • Really good value for the money.
  • It will probably be enough for your pond.
  • It treats up to 4,800 gallons.
  • Easy to use
  • It works as advertised.
  • It is the cheapest per ounce there is.
  • It’s safe for fish


  • It’s made by a less reputable company.

What are algae? Is it bad?

Algae usually harm little more than your pond’s aesthetic appeal. But left unchecked, they can quickly become a hazard. These aquatic lifeforms often soak up the nutrients from your pond, leaving fewer for your plants and fish. Some also release toxins when their numbers become too great.

In small numbers, these organisms are a normal part of every aquatic ecosystem. Since they contain chlorophyll, they contribute to oxygen production. It is good for your pond. But you might have to take immediate action when they grow out of control.

Why do they grow?

Algae grow naturally in both fresh and salt water. Though many sources claim that rainforests produce the most oxygen, this isn’t true. Over half of it comes from algae.

However, certain factors promote their growth. The most notable contribution is the content of nitrogen and phosphorus. These two nutrients help these aquatic organisms grow, often to a great extent. But where do these nutrients come from?

Both nitrogen and phosphorus are essential for plant growth. They are, thus, the key nutrients that make up commercial fertilizers. You can find fertilized soil everywhere, from lawns to pastures.

When you choose to build a pond, the odds are the soil already contains high amounts of these nutrients. It is one of the main reasons why many people struggle with algae control. Sunlight is also essential for photosynthesis. Sunny areas are therefore more susceptible to this problem.

Fortunately, you can take preventative measures to keep this issue in check. We’ll discuss this in the later sections of this article.

Make sure to look out for the 4 signs:

  1. water discoloration
  2. Surface foam
  3. Hair-like blankets
  4. Dead fish

4 signs of Problems

These organisms in your farm pond are hard to miss. Many will change the way your pond looks. If they grow out of control, they might also endanger the fish and plants in the ecosystem.

Here are the 4 signs you might need to act against this aquatic menace:

Water discoloration

They can change the color of your pond water. The most common color is green, which makes it resemble pea soup. Sickly, blueish color is also common.

Foam or other shapes on the pond’s surface

They often form shapes on the surface. If you notice foam, scum, or mats, you should look for water algae treatment options. Some may form shapes resembling spilled paint. It is a clear sign of overgrowth.

Hair-like blankets cover the pond features.

Some types resemble tiny strands. These can accumulate on nearby rocks and plants.

Dead fish

In the worst-case scenario, the toxins they release will harm the whole ecosystem. At this point, your fish might start dying.

Signs to look out forWhat’s going on?
Water discolorationIt can look like pea soup.
Surface foamIt can look like spilled paint.
Hair-like blanketsMake sure pond features aren’t overgrown.
Dead fishDead fish is never a good sign.

Pond maintenance

When you choose to build a farm pond, it’s more work than digging a hole and filling it with water. It is an ecosystem that needs constant attention to survive. Without proper maintenance, it will become inhospitable for both plants and fish.

Here are the 6 key tips for excellent pond maintenance:

Add an aerator

Waterfalls and fountains keep the water moving. As it flows, it soaks up more oxygen. Apart from benefitting your fish, it also reduces the amount of nitrogen and phosphorus in the water. A good aerator can greatly reduce the need for manual maintenance.

  • Getting an aerator
  • Remove algae blooms
  • Bacterial treatment
  • Phytofiltration
  • Pond dye
  • Keeping animals away

Remove algae blooms manually.

These blooms usually pop up every spring. Luckily, you can remove most of them manually. You can use either rakes or skimmers for this task.

Keep farm animals away from the pond.

We all know where fertilizer comes from. And since it contributes to unbridled growth, you shouldn’t let your farm animals come near it. Large domestic animals can also deform the banks.

Use bacterial treatments

Some bacteria can reduce both undesired growth and the odor it produces. We recommend products such as GreenEX or Microbe-Lift PBL for this kind of water algae treatment.

Use pond dye

Black and blue pond dyes absorb some sunlight, reducing the rate of photosynthesis. It can make your annual spring maintenance much easier to carry out.

Use phytofiltration

Phytofiltration involves using plants that absorb nutrients from the water. It leaves fewer of them for algae, effectively reducing their growth. Our recommendations are water willow, water snowball, and hibiscus.

Barley straw

Barley straw is an excellent form of water algae treatment. Though not an algaecide, it does prevent new algae from growing. It’s thus considered an algaestat.

While scientists don’t yet understand all the details, they theorize that barley straw releases chemicals into the water as it decays. These chemicals inhibit the growth of algae. The main appeal of barley straw is that it’s selective. It’s completely harmless to plants and animals.

You can purchase barley straw at any farm supply or feed store. Keep in mind that its availability depends on the season. You can also get your hands on it online, though at a higher price.

To reach maximum efficiency, you should use barley straw in spring. The water should be warm to initiate its decay. We recommend using 4 to 5 bales per surface acre of water. Cut them up into small pieces to speed up the decay. Then, place them in tiny sacks. Ideally, they should float a few feet beneath the surface.

Barley straw is particularly effective against planktonic algae.

Copper sulfate

Copper sulfate is an excellent algaecide for ponds. Unlike barley straw, copper sulfate works wonders against both filamentous and planktonic algae. It both kills them and prevents their regrowth. Its only drawback is that it’s much less selective. Improper doses can wreak havoc on the whole ecosystem and kill fish and plants alike.

You can find copper sulfate at any agriculture retail store. Alternatively, you can buy it from online vendors.

You should apply copper sulfate twice, with at least 5 days between each application.

Copper sulfate comes in the following 3 forms:

Granular/Crystal Form

Granular copper sulfate is very easy to use. You generally need 5 pounds of this substance per acre. Before you apply it, make sure you dissolve the granules in hot water. Otherwise, the granular will sink to the bottom. It leaves the surface algae unharmed.

Liquid Form

It is the strongest form of copper sulfate. We recommend using it if the growth is completely out of control. You should dilute 1 gallon of this algaecide with 10 gallons of water for the best results. Then, you just apply it by using a broadcast sprayer.

Keep in mind that liquid copper sulfate is harmful to some fish, such as koi and goldfish.

Power/Dust Form

It is similar to the granular form. However, you can only use it if your pond’s temperature lies between 60 to 100 F. Otherwise, it won’t work as intended.

One drawback of this dust is that it scatters easily. Wind can easily carry it to nearby land and contaminate it. Copper sulfate is harmful to animals if they breathe or ingest it. It goes for humans as well. To avoid any lung complications, make sure you wear a mask when you use it.


While algae occur naturally in every aquatic ecosystem, they can become a huge issue if they grow out of control. At night, they consume large amounts of oxygen. Larger ones can also cover the surface and prevent sunlight from entering the pond. Some types also release toxins that can kill both your plants and fish.

Though you can remove them manually, algaecides are your best bet against them. These chemicals are great for removing algae without harming the fish. But the battle doesn’t end there. You need to practice good maintenance habits to ensure the issue doesn’t return later. Adding aerators and certain types of fish can make your job much easier.

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