How to Control and Get Rid of Pond Algae

Although algae may be a potential source of biofuels for our next-generations, it can sometimes be a nuisance to pond keepers/owners. Without proper planning and prior knowledge, controlling pond algae can prove to be a daunting task. If you have tried it before, you definitely know what I mean.

In high density, algae blooms can cause poisoning, depletes oxygen in a pond and also causes water discolouration. This will, in turn, affect the water quality thereby making it unsafe for animals, fishing, swimming, etc.

However, in this article, we’ll be looking at several effective and efficient ways you can use to control and also get rid of any algae that grow in your pond. We aim to guide and help you learn the best ways to deal with algae growth as a pond keeper/owner.

Here is what you should consider when deciding how to get rid of pond algae. Read on to find out more:

The equipment for controlling pond algae

Almost all new ponds lack proper balance of animal life, plant life as well as other common biological functions. This makes combating algae a major problem for any new pond keeper/owner. The new Pond keepers/owners will have to search for ways to combat the algae, making algae control the most discussed topic among new pond owners.

The first and most essential step towards an algae-free new pond is to use proper and appropriate equipment throughout the whole algae control process. For instance, when installing a pump in your pond, it should be capable of moving about half of the volume of the pond to create a water garden, take a look at our range of recommended solar pond pumps.

A water garden is a pond that contains a lot of fish and also other plants. However, there are other types of ponds that contain a lot of fish but very few plants and thus need more filtration as compared to a water garden. A good example of such a pond is the koi pond.

For the koi pond, it’s advisable to move the entire volume of the pond per hour. In addition to moving the large volume of water, ensure it undergoes filtration. The pump you use should be able to pass water through a filter that is sizable depending on your pond size.

There is a guide to selecting the perfect combination of filters as per your pond size. Note that biological filtration usually takes several weeks if not months to fully mature to a point where it can make a significant improvement to the quality of water in your pond. Filters should run 24/7, nonstop, for the filtration process to work.

Additionally, during the winter you’ll want to make sure that you’re using a pond heater & de-icer to prevent the accumulation of harmful gases in the pond water.

How to construct the perfect pond

Take a read of our 7-step guide on how to build a small pond in your back garden.

However, as a rule-of-thumb, for clean, high-quality water, the construction of a pond is an essential factor that must be considered. Here is what you should keep in mind:

• A pond has to have roughly 40% of its entire surface as a deep zone. This deep zone is supposed to be 3 feet or even more for koi ponds and 2 feet for a water garden.

• 30 % of the pond needs to be at an intermediate depth while another 30 % should be about 1 to 1 feet deep

• For easier removal of pond debris, it’s recommended that the pond should have a slight slope.

• Always use Pond skimmer to remove up to 85% of your pond debris before it sinks, and make sure that you use a high-quality pond liner.

To avoid rainwater from flowing over your yard and into the pond, you should be keen and careful during the construction process. Rainwater flowing into ponds is among the most common reasons for the growth of algae. This is because rainwater brings about runoff water that erodes and carries several organic remains that may contain major nutrients that feed and help the algae thrive.

Besides, chemicals and fertilizer will be eroded into the ponds leading to even bigger problems. It is possible to alter the surrounding of your pond to ensure water runoffs don’t flow into it even if you have already constructed one. However, you can’t do anything about your pond depth if you have already finished constructing it.

Reduction of algae levels requires that you don’t build ponds using marble or limestone. This is because marble and limestone contain high pH that can cause more algae growth.

How to maintain your pond, to prevent the forming of algae

It’s a normal procedure for you to maintain your pond now and then. It’s also normal to notice a buildup of debris at the bottom of your pond. If the sludge buildup doesn’t exceed about ¼ inch, it’s not necessary to consider physical removal.

If you had constructed your pond properly, most of this debris would recollect into a small area which will be easy to remove. You can use a net to remove dead leaves and other course materials, i.e., string algae. In case the debris is very fine that a net can’t remove it, use a pond vacuum.

There are several products that you can use to reduce sludge in your pond. For example, you can use enzyme and bacteria products such as PondZyme, Simply Clear, EcoFix or other products from Microbe-Lift to improve fish conditions, reduce pond odor, improve the general water quality as well as reduce the quantity of sludge that may lead to algae growth.

Pond maintenance varies from time to time according to different seasons. For instance, there is a lot of work that needs to be done to the pond during summer and spring. During winter and autumn, you only have to make the pond livable by not allowing fish to hibernate due to freezing.

Number and type of plants in the pond

In case you don’t have a koi pond, ensure you have the right number and type of plants in your water garden. Plants like Anacharis, floating plants and other underwater plants get rid of excess nutrients found in the pond. They do this by absorbing the nutrients for self-gain and growth, hence algae starves because its source of food is no more.

Cover about 2/3 of your pond surface using plants that make the pond water surface shaded. Good examples include water lilies and floaters, i.e., Water Hyacinth, Water Lettuce, etc. By covering the water surface, these plants minimize the penetration of sunlight into the pond which, in turn, starves algae due to inadequate sunlight and also helps in keeping the pond water cool.

It’s worth noting that algae could be still present in your pond even if you use the right type and number of plants as well as proper components, but you don’t have a lot of fish. This happens mostly when the pond is quite young. During the first years of a young pond, you can use other methods to control algae. If the pond isn’t entirely emptied and refilled, as years go by and it matures, the presence of algae reduces.

Pond algae treatment procedure

For proper pond algae treatment, pond keepers/owners should use beneficial enzyme and bacterial products as earlier mentioned. This should be done regularly while the pond matures. In case you have some issues with green water, install an ultraviolet sterilizer. An ultraviolet sterilizer guarantees you 100% clean water as the pond matures.

Here are some products you can use in treating pond algae:

i. Using GreenClean for Filamentous algae

There are several types of algae, i.e., filamentous algae, planktonic algae, macrophytes algae, etc. However, Filamentous algae are the most common of all the others. This type of algae is mostly found attached to sticks, leaves, mud, rocks or other plants. As it grows, it stretches out to the surface, breaks up and causes new growth that is then transported throughout the pond by wave and wind action.

Filamentous algae occur in many forms, e.g., shot and furry, stringy and long and even in the shape of a mat or a web. It’s the short algae that usually covers almost everything in a pond. It’s velvet in color and very beneficial because it makes the pond look natural. It produces oxygen during the day, and most fish depend on it although it uses nutrients from pond water.

Filamentous algae can’t be eliminated at once with plants and fish in the pond. String algae are even harder to deal with because it can even coat an entire waterfall. Nonetheless, where possible, it can be removed physically from the pond. Due to the high intensity of sunlight on shallow streams and waterfall, filamentous algae will most likely thrive. This is because the sun will be providing more light and heat as well as constant nutrient supply flowing through the waterfall or shallow stream.

The best and most effective way to treat filamentous algae found on streams and waterfall is using GreenClean. It fights and prevents algae from blooming as well as releasing essential oxygen to pond water while it biodegrades. It is formulated without the use of chlorine or any other harsh chemicals to ensure they don’t affect the aquatic ecosystem negatively.

ii. Using Algaway

While your pond is maturing, Algaway is a very useful product in controlling algae. Algaway is an algaecide that helps control string algae. However, you should not use Algaaway in ponds that contain ornamental snails, mollusks, shrimps and other crustaceans.

This algaecide is meant for self-contained fountains and ornamental ponds that don’t have an outflow. Before the addition of Algaway to a small pond that has excess algae, ensure you clean off some excess algae. This will help you minimize the quantity of organically decaying matter.

iii. Using Barley Straw

Use of Barley Straw, as well as Barley Straw Extract, is also useful and efficient in improving the conditions of water in ponds. Barley Straw doesn’t kill previously existing algae. Instead, it inhibits the growth of new algae, making it very effective for use in new ponds.

Although it’s not clear how Barley Straw works, it’s believed to produce some chemicals that prevent the growth of algae. This occurs due to oxygen presence and when it’s exposed to sunlight. Barley Straw doesn’t affect other aquatic plant growth at all.

When it’s applied to a pond that has cold water, for example, less than 50F, the Straw will take 6 to 8 weeks for it to start producing the chemical that inhibits the growth of algae. If applied to warmer water, for example, 70F and above, it will probably become effective in 2-3 weeks.

You should apply about 2 to 3 bales of Barley Straw per acre of the pond. This translates to about 10-25 grams for every square meter of the pond area. The pond water depth isn’t necessarily important when applying Barley Straw.

iv. Using pond dye

Pond dyes work by helping color water blue-green or dark-blue. This coloring creates a shade for the pond water hence reducing the quantity of sunlight absorbed by algae. Black and blue dye are the best for use in lakes and large ponds due to low cost although it can also be used in other smaller ponds.

Note that Black dye may not help you if your pond is muddy because it might not penetrate suspended articles. However, a blue dye can readily penetrate suspended particles.

v. Using Fountec

Fountec improves the quality of pond water by keeping it clean as well as removing algae. In case your pond doesn’t have fish yet, this is an excellent product to use because it’s safe for other animals, e.g., pets that may drink water from the pond. However, it’s not safe for fish.

vi. Using pond Ionizer

This is among the most recent algae control products. A pond ionizer uses electric charges that run through an anode that is made of copper. The anode is placed in a line of water flow where it releases copper ions that minimize the growth of algae.

Whenever you are treating algae, it’s critical to make sure you abide by the product package directions and ensure there is adequate aeration in the pond. Besides, you should not overfeed fish or add a lot of fish that your filter and pond can’t support.


Do you now know how to control pond algae? Simple, isn’t it? With the right knowledge and proper planning, algae control will be quite simple. You should note that fish foods and fish themselves add nutrients to ponds. These are the nutrients that feed algae.

In summary, here are some points to note from this article:

• Sludge that is less than ¼ inch at the bottom of a pond should not worry you. Always keep down organic load in the pond by keeping any runoff out and also vacuuming any already accumulated sludge.

• There should be no overfeeding or keeping a lot of fish than the pond can support

• Ensure you install a bigger biological filter and allow some time, i.e., several months, for it to work.

• The aquatic plants you use should be able to act as floaters, shade as well as underwater plants to help in getting rid of excess nutrients. These plants should be of the right type and amount.

• Always use biological treatment methods and allow them some time to work effectively. Remember, some of the outlined methods, e.g., Microbe-Lift in this article take time.

• Barley Straw Extract is used in ponds with not more than 3000 gallons while Algaway is used to get rid of existing algae problems pretty fast.

• Always install and use the ultraviolet sterilizer to effectively control green water algae.