5 Ways to Get Rid of Algae in Your Pond


If you are facing an algae outbreak in your pond, you are aware that it can be one of the most disheartening things you will face as a water gardener. What you intended as a thing of beauty has turned into an eyesore. Your sanctuary has been invaded by an unwelcomed enemy. Even though it may feel like it at the moment, you are not powerless.

Here are 5 main things you can do to eliminate algae in your pond:

1. Starve the Algae

The more you weaken an enemy, the easier it is to defeat. If you get rid of excess nutrients in your pond, you will at worst slow down the algae growth, and at best eliminate it all together. The best way to remove excess nutrients in your pond is to:

Clean Out Your Pond

Eliminate as much of the organic debris in your pond as possible. Rotting plants, animals, algae, sludge, and fish food all serve to raise the level of nutrients (nitrates and phosphates) that algae need to grow. Eliminating excess nitrates and phosphates and preventing more from entering your pond is an essential place to start.

Limit Your Fish Levels

Overstocking your pond with fish can significantly increase the amount of nutrients in your pond. Excess fish food, fish poop, and even the act of fish respiration in the water increase levels that ultimately end up fueling algae growth. Plants consume the same nutrients as algae. Having a heavily planted pond reduces the amount of food available to the algae.

Use Bacterial and Enzymatic Additives

There are consumer products available that help establish a healthy ecosystem in your pond so that excessive waste and nutrients are processed more efficiently by the pond system. Products such as Aquascape Beneficial Bacteria, Aquascape SAB, Laguna Sludge Control, and Laguna Bio Booster add helpful ingredients that occur naturally within ponds. Think of these products as giving Nature a helping hand.


Ensure Your Pond Is Runoff Free

Lawn fertilizer and pet feces contain the phosphorous and nitrogen that algae uses for food. If your pond sits in a low point in your yard, you need to build up the edges so you don’t get runoff.

Change Water Frequently

There are few more effective ways to reduce the excessive levels of nutrients in your pond than to do frequent water changes. Swapping 20 to 30% of your pond water every week removes the equivalent amount of nutrients from your pond and replaces it with nutrient-free water. Pro Tip: Water from your pond is excellent for use on your lawn or flower bed because it is innoculated with beneficial bacteria.

Note: While most municipal water contains no phosphates or nitrates, it is advisable to test your water with an at-home test kit to ensure this is the case in your area. If you are filling your pond with untreated water from a dugout or ditch, testing is a must.

2. Limit Available Sunlight

Another way to weaken algae is to starve it of sunlight. Algae, being photosynthetic, can’t process nutrients without light so limiting direct sunlight to your pond will inhibit its growth. You can limit the sunlight that reaches pond algae by shading your pond with:

External Structures: Buildings and Trees

Shading your pond with trees or other permanent structures slows the advance of algae by limiting direct sun to only a few hours during the day. If you’re reading this article because you already have an algae outbreak, this suggestion is more difficult to implement. However, if you are in the planning stages or are willing to plant trees or build a building of some sort, this option.

Live Plants

Live plants are extremely effective in your battle against algae. Planting or placing large amounts of surface covering plants such as hyacinths, water lettuce, and water lilies* in your pond provide shade directly onto the surface of your pond, preventing sunlight from penetrating down to where the algae dwells. Water plants also providing the secondary benefit of competing for the same nutrients as the algae (see point 1).

Tall marginal plants such as bulrushes, cattails, and irises also are helpful in providing some shade at certain points throughout the day, but are less effective than surface plants.

Water Dyes

Darkening your water so the ultraviolet rays of the sun cannot pass through the water can quickly clear up your algae problem. There are numerous dyes in a wide variety of colours that have been developed specifically for this purpose.

Water dyes are a very popular solution with many pond owners because of their effectiveness. Others shy away from this method due to its unnatural appearance and how it impairs the view of fish and other pond inhabitants.

3. Attack Algae with Circulation

Algae loves stagnant water, particularly the high carbon dioxide (CO2) levels that it inevitably contains. In stagnant water, CO2 levels tend to be higher and oxygen (O2) levels tend to be lower, setting up a great environment for algae to thrive. Increasing the circulation in your pond will dramatically help your situation. You can increase pond circulation by:

Increasing Your Pump Size

You should be circulating all the water in your pond at least once every two hours. This is a minimum turnover – more is better. Not only does increasing the size of your main circulation system allow for greater oxygen absorption (which is great for your fish and overall health of your pond ecosystem), but it also allows for CO2 and other gases to be released out of the. Checking the flow rate of your pump and upgrading if necessary is vital in your fight against

Adding Water Features and Aerating Devices

Water features that increase the surface agitation and disperse highly oxygenated water throughout your pond are great weapons in the battle against algae. Pond waterfalls, spitters, and fountains are highly effective in both breaking the surface tension of your pond and circulating O2 rich water throughout your pond. The fact that they look beautiful as well is a welcome bonus.

Aeration pumps for ponds with air stones and Venturi systems (these can be added to your circulating pump) are also a good way to fight stagnation. Although less decorative, aerators are effective in directly dispersing O2 rich air into your pond water.


4. Use Water Additives

Some of the greatest advances in algae control over the past few years have come in the form of liquid and granulated additives. Some of these water additives are new forms of old remedies and others are creative new approaches. All can be helpful in your quest to rid your pond of. Some common, helpful water additives are:

The use of barley straw as algae control in ponds has been practiced for a long time. Barley straw in extract form, however, is relatively new and eliminates the need to wait for the straw to decompose before it is effective. Unfortunately, barley straw in any form does not kill algae.

The effectiveness of barley straw lies in its ability to inhibit the growth and reproduction of algae cells. Therefore, barley straw is best used to slow algae growth while using other methods to eliminate it.

As a preventative measure is how barley straw and barley straw extract really shines. Adding it early in the spring before algae begins to grow can keep the algae from ever getting a foothold in your pond.

Hydrogen Peroxide Based Treatments

Hydrogen Peroxide products, usually found in a dry granular form (Laguna Pond Clean and Aquascape Ecoblast), have been a valuable asset in the war on algae. These products are highly satisfying to use as the results are virtually instantaneous.

The hydrogen peroxide breaks down the cell walls of the algae when it comes in contact with it, creating an almost magical reduction of algae before your very eyes. If applied directly to the base of where string algae attaches to the pond walls, it will break algae loose allowing for easy removal.

These products are great for quickly reducing the amount of algae present in your pond, but do nothing to prevent it from coming back. For maximum effectiveness, hydrogen peroxide based treatments should be used in conjunction with other additives such as barley straw extracts and bacterial and enzyme products.

Bacteria or Enzyme Based Treatments

There are numerous additives available on the market that use a mix of bacteria and enzymes to control pond algae, such as Aquascape S.A.B. and Laguna Bio-Sludge Remover. These products boost the level of naturally-occurring microorganisms and chemical properties in your pond, speeding up the breakdown of sludge and consuming nutrients that algae use to grow.

Most of these products recommend weekly or biweekly dosing for maximum effectiveness and you should take this recommendation seriously. Using bacterial or enzymatic products in conjunction with other methods – hydrogen peroxide additives, barley straw, increased circulation – increases effectiveness and improves success in an algae outbreak.

5. Utilize Technology

Using technology to eliminate algae has become very popular in recent years. Although technology can cost more upfront than other methods, its effectiveness is unmatched.

Two of the most common forms of technology used in algae control are:

UV Sterilizers

UV sterilizers are the most popular pieces of equipment in the fight against one of the most difficult forms of algae to eliminate – suspended algae. Suspended algae manifests itself as the sickly looking green water that makes your pond water impossible to see through. UV sterilizers work by circulating pond water over an ultraviolet light which kills the algae cells present in the water. A properly sized UV sterilizer in your pond system will quickly clarify your water and insure that you never have to face an outbreak of suspended algae again.


Ionizers, such as Aquascape Iongen Water Clarifier, are a relatively new treatment for algae problems. The advantage of these systems is that they are effective against all forms of algae – suspended and string.

Ionizers work by releasing ionized copper into the water, a metal that is toxic to algae. It is vital, however, to maintain the proper concentration of copper without reaching levels where it becomes toxic to your pond fish. This requires regular testing with a copper test kit and subsequent system adjustment to be both safe and effective. In your campaign against the scourge of algae, the more weapons you bring to the battle, the more assured you are of victory. Do not hesitate to be ruthless in your fight and soon your sanctuary will be restored to the thing of beauty it was intended to be.

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