Manage Algae With The Best Pond Algae Killer

By Algal Web

Updated on

This content might include affiliate links that could provide compensation if you click or sign up.

As an Amazon Associate I earn from qualifying purchases.

Algae in a pond aren’t all bad. The bacterial growths are helpful for oxygenating the water, it acts as a natural habitat for insects and lots of aquatic insects and fish species feed on algae. But pond owners do need to keep a close eye on their fish ponds because algae grow rapidly and can soon take over your pond. Too many algae can cause issues with the water quality since it can result in nutrient pollution and can cause unpleasant odors. 

There are quite a few different types of pond algae killer products available on the market. In this guide, we are going to take a look at the best methods and product types to use for maintaining an ideal ecosystem. 

 Identify Algic Bacteria

Not all algae treatments and killers will work on all algae types. You need to identify the algae bacteria you have before you can start treating your pond. There are many different types or groups of algae. The green group or clorophyta group of algae, for example, has over 7,000 species of algae alone. 

These bacterial growths are divided into two different physical categories:

Planktonic Algae

Planktonic algae species can only be effectively identified under a microscope. The blooms of these growths can seem like a paint-like scum on top of the water surface but the entire water column can turn green with a “pea soup” look. 

Filamentous Algae 

This type of algae seems like long stringy hairs or can look cotton-like. String algae types have a thread-like appearance and tend to cling to underwater surfaces. Cotton-like varieties can form green mats on the water surface and can sometimes attach to other materials like rocks. 

Some filamentous algae can be bright green and slimy while others can look more like horsehair with a harder texture that feels a bit like steel wool. 

Another form of algae you should be aware of is Chara. This type of algae is often mistaken for aquatic plants or submerged plant species and it can be the most challenging algae type to treat. Chara or stonewort grows on the bottom of lakes and ponds and resembled tangled plants. The algae form a carpet on the bottom of the pond and have a coarse texture and a musky odor. 

Chara algae can only be treated in its early growth stages because it will soon develop a natural resistance to algaecide after which it will be very hard to treat this alga. 

Types of Pond Algae Killer Treatments

Once you identified the main type of algae species you have, you can get to work on finding the right treatments. Here is a quick look at the best algae treatments for different forms of algae. 

Treatments That Completely Eradicate Algae

Some pond algae treatment products are chemically engineered to destroy all algae particles of any form to completely rid your pond of these types of bacterial growths. Chemical algaecides can be a bit harsh on your ecosystem since they can result in oxygen depletion or even damage your fish which is why you need to be very careful when using these algaecides. Harsh chemicals can also affect the health of certain aquatic species. 

There are quite a few common types of algaecide products available on the market like the following:

Algaecides with active oxidizers

Most algaecides on the market act as oxidizers. Products like Aquascape Algaecide Treatment destroy the cell walls of algae and will quickly destroy just about any type of algae particle in a short time. Algae particles will however stay in your pond after treatment. This can result in clogged filters or settlements on your pond floors. 

It is very important to properly clean your body of water after using an active oxidizer algaecide because the waste products will eventually decompose and can affect the oxygen levels of your water.

Copper-based solutions

Copper-based algaecides like Crystal Bue Copper Sulfate Algaecide are not as effective for killing all algae but will work for longer. With these algaecides, you need to maintain a certain level of copper in your pond. Copper-based treatments like copper sulfate will prevent future growth but won’t kill your existing algae. These treatments can also be expensive and can be toxic to the wildlife which is why oxidizers are preferable. 

Important tips for using algaecides

Algaecides can affect the animal life in your pond because the dead algae eventually decompose which results in poor oxygen levels. Dead algae particles can also settle on the pond floor and can affect your pond water quality. Here are a few good tops to try when you are using these pond algae control products.

Section your pond

Don’t treat the entire pond at once Divide your pond into sections so you can avoid poor oxygen levels. You can treat a different section every 7 – 10 days if needed. Repeat this process until your algae is under control. 

Use an air pump during treatments

Consider an air pump if you are using an oxygenation treatment. The air pump or aerator will maintain adequate oxygen levels so your fish won’t suffocate or stress too much. Good aerators include water features like waterfalls, fountains, and air pumps. Air pumps with diffusers are ideal for oxygenation treatments.

Keep the filter clean

When your pond is treated for algae, a lot of dead bacterial particles will be left behind. These particles can make your pond look messy and will eventually break down to create low oxygen levels. they can also clog your filtration system. You should clean your filtration systems every day if you are using an algae killer treatment. 

Remove deposits

Clear out sludge, dead algae, and other green waste from the bottom of your pond. This will reduce the release of harmful substances that could affect your water quality or cause bad odors. If you have a lot of sludge in your garden pond then you can consider natural bacteria. These treatments can break down the sludge over time.

You can also use a vacuum cleaner to remove sludge and dead algae to keep your pond free from excess nutrients and waste. 

Treatments That Naturally Control Algae in Ponds

If you want to treat excessive growth of algae without causing negative side effects like poor oxygen levels or toxification to your pond fish species, then you consider a natural treatment.

These treatments are best suited for treating filamentous algae species that you might want to control but do not want to completely destroy.

Here is a quick look at natural treatments to control algae growth. 

Barley Straw

Barley straw pellets are a natural product that changes the PH of the water to make it less suitable for algae growth. This method only works if you apply a constant supply of barley in your pond and it won’t have enough of an effect to treat extreme algae infestations. 

Pond Bacteria

Pond bacteria are often used along with barley straw for more efficiency. Bacillus bacteria are introduced to fish ponds to outcompete unhealthy algae species. The algae in your pond are constantly competing for nutrients. By introducing Bacillus bacteria algae, the other algae species will be deprived of nutrients and will start to die out. 

Beneficial bacteria are usually sold in liquid and powder form. You don’t have to worry about overdosing on this product because the bacteria adapt to your pond environment. The nutrients in your koi pond can only support so many algae which means overdosing is impossible.

A winter-blend of beneficial bacteria is ideal because these bacteria growths are more resilient to cold temperatures and can help decompose leaves and other debris that fall into your pond which can help keep your backyard pond nice and clear. 

Proper Fish Care

Some fish species like koi fish or Asian triploid grass carp feed on algae. But they will only do so when their other food supplies are limited. By reducing your food supply as the temperatures decline for winter, you can encourage your fish to feed more on algae. This can keep the algae count nice and low. 

Proper Filtration Systems

Pond filtration systems can also keep your koi pond algae free. This is especially important if you have a lot of fish in the pond. In addition to a good filtration system, you also need to regularly clean and maintain your filters or your systems won’t function quite as efficiently. 

Avoid Excess Nutrients

You can also control the growth of algae by limiting excess nutrients in the pond water.

Keep grass clippings, leaves, fertilizers, and other organic plant matter out of your pond. You should also prevent erosion that could result in a nutrient deposit into your fish pond. 

You can also add aquatic plants or pond plants like pickerelweed, sedges, or rushes to your healthy pond since these growths will absorb some excess nutrients that could keep your algae from growing rapidly. 

Treatments for Planktonic Algae

Some algae killers like pond clarifiers are designed to kill free-swimming particles like planktonic algae but won’t do much harm to string algae and blanket weed. With this type of treatment, you can create clear koi pond water since the treatment is designed to kill the algae that cause that murky green water but still preserve healthier types that fish and aquatic insects feed on. 

Pond clarifiers can be combined with other natural algae treatments to help you control other types of algae while combating green pond water. 

Final Thoughts

We do hope that this guide helped you find a good pond algae killer so you can maintain a healthy ecosystem and boost the health and growth of your beautiful fish species. If you want to learn more about algae or find other solutions to control algae growth then you can also have a look at some of the other guides on our website. AlgalWeb is packed with advice to help you control, clear, or boost algae in your water garden.

Amazon and the Amazon logo are trademarks of, Inc, or its affiliates

Leave a Comment