5 Common Types of Pond Algae

5 Common Types of Pond Algae

Algae are one of the most underrated and unappreciated parts of a pond’s ecosystem. Of all types that can grow in a pond, euglena, blue-green, string, green water, and Chara algae are the most common. While most people assume that algae is bad for ponds—and an overgrowth can be harmful—it can be beneficial in the right amount, oxygenating water, feeding animals, and much more. 

While certain species bring benefits to a pond, it’s important to monitor algae growth. When it’s allowed to grow unchecked, algae can turn a beautiful pond into an embarrassing, smelly eyesore. It’s easy to prevent the overgrowth of algae. As with almost anything else, your first step toward pond algae and weed control should be to find out what you’re dealing with. By learning about the most common types of pond algae, you can prepare for it and prevent it from becoming a problem.

Planktonic or Green Water Algae

Of all the types of algae we’ll cover here, this is one of the most beneficial. In small doses, green water algae can improve a pond’s health. It provides nutrients, oxygen, and nourishment for ponds and the animals that live within. Blue green algae also shades the pond’s bottom, which prevents invasive plants from taking hold. When those nutrients become unbalanced, though, problems may arise.

It’s easy to spot an overgrowth of blue green algae, because your pond’s water will turn murky green. Determining when a bloom starts, however, is a bit more challenging. Planktonic algae are inert in small numbers, so it’s important to keep the pond’s water balanced. If it isn’t, it will end up brown, blue green, or a shade in between. Blue green algae overgrowth can be prevented with adequate maintenance and filtration.

String or Filamentous Algae

It’s like a bad hair day for your pond. Filamentous algae is sometimes referred to as moss or pond scum, simply because that’s what it resembles. You will spot this type of algae as it gradually rises to your pond’s surface in long, green, and wavy mats. 

It’s as if someone covered your pond with a blanket—and not a warm and cozy one. A pond will suffer if it has an overgrowth of string algae, but as with other types, a little bit goes a long way. In small colonies, string algae oxygenates water and feeds pond animals. Too much, though, and your pond’s aesthetics, water quality, and mechanics will suffer.

When determining the nature of a string algae problem, look near the bottom and edges of the pond. Filamentous algae starts growing there and rises to the surface with time. It’s easier to prevent it than it is to remove it, as is the case with planktonic algae. Control it by adding beneficial bacteria to the pond, removing any visible growth, and monitoring water quality. With these steps, you’ll prevent most string algae problems.

Blue-Green Algae

Also known as cyanobacteria, oscillatoria, and attached-erect algae, this type is far from ordinary. It comes in several colors other than blue-green, such as yellow, brown, and red. Each color is equally bad for a pond’s health.

Water quality is a primary factor in the overgrowth of this type of pond algae. Too many animals, inadequate filtration, and low oxygen are a few things that can lead to a bloom of blue-green algae. Not only will this kind of algae make a pond look bad, but it will also kill fish—which will make things smell bad. If you’re dealing with an outbreak of cyanobacteria, don’t touch the water, as it can cause sickness.

While blue-green algae may sound like a big problem, it’s good for a pond in small amounts. Attached-erect algae grows naturally in ponds all over the world, and it’s usually best not to mess with Nature. 


If you take care of a koi pond, it’s not necessary to worry about this algae species. However, that doesn’t make it less of a hassle to address. Euglena outbreaks happen suddenly, as if the algae were hiding and waiting for the right time to strike. This kind of algae bloom typically looks bright red, and it can be harmful to pond animals and plants.

Removing euglena is tough because you’ll have to use chemical algaecides or drain the entire pond. These products can be dangerous to plants and fish, so we suggest the latter method. While you’re draining and cleaning the pond, take the time to inspect it for components that aren’t working or will need to be replaced. Do your part to prevent euglena overgrowth by including an ion generator, which balances out the water with copper, a natural algae fighter.


This type of algae is surprisingly beneficial. Chara is sometimes called muskgrass because of its strong, garlicky smell, and it’s often mistaken for an aquatic plant because of its appearance. Though it may seem as if Chara is trying to confuse you, it’s really helping your pond. This species of algae feeds animals, oxygenates water, removes pollutants, and holds down the sediment that can make water murky. Though it’s certainly helpful in this regard, it’s important not to let it grow wild, or it will take over the whole pond.

Keeping Pond Algae Under Control

The key to effective algae treatment, regardless of species, is to bring an algaecide and an active bloom together. If pond algae is broken or cut into small pieces, it’s harder to treat. Algae lacks a true root system, and it will continue to multiply when it’s cut. 

We recommend a one two punch for treating ponds that are out of control with algae. The first thing is aeration. Excess algae is usually caused by excess nutrients at your pong. Fish poop, dead plants, bugs, etc on the bottom of your pond build up if the water is still and there is no aeration to keep the water flowing. Then long term this will prevent excess algae, and to really get rid of it quick we recommend our Pond Boost which helps immediately improve water quality and quickly. Get rid of excess nutrients, sludge, and algae. 

In Conclusion

No matter which kind of algae you’re dealing with, all the species listed above will look unsightly when they’re allowed to grow unchecked. With regular checkups and frequent maintenance, it’s possible to keep your pond looking like an outdoor paradise. Count on the experts at Living Water Aeration to offer the tools, supplies, and expertise needed to maintain your pond all year long.

You can see our products
See Products
Back to blog

Leave a comment

Please note, comments need to be approved before they are published.