Select Page

If you have walked past a pond, you may have seen algae on top of the water. Some of it is microscopic but can build up into a dense covering. Certain species of algae can even move around and swim.

Pond algae are one-celled plants. You can spot them floating on the surface of ponds and see them attached to plants around the pond and on rocks.

Pond algae are very similar to seaweed found on the seashore and are related, with many belonging to the same group. Algae can not only be found in ponds but many freshwater areas.

If you want to clear algae from your pond, then there are some great products on Amazon.

Algae is an essential food source along with plant material such as leaves that fall into the water. As a photosynthetic plant, the algae uses the energy from the sun to produce sugars that animals eat as a source of energy. Although animals eat not all algae, some fall to the pond’s bottom, indirectly becoming part of the food web. Bacteria on the pond floor, along with some animals, will then eat the debris.


Diatoms are a major group of microscopic algae. They are either made up of a group of cells and a cell wall made of silica or single cells with a silica wall.

The cell walls form together to make various shapes, including star shapes, boat shapes, and zig-zag shapes. When they die, the diatoms’ skeletons fall to the pond’s bottom. When these are fossilized, they can be used in a variety of ways. The deposits, known as fullers earth, can be mined and used in different ingredients in paints and toothpaste.

If you have a shed, then you have probably seen some spiders in there. Do you know what else may be living there? Find out here


Along with the diatoms on freshwater ponds, you can often find another tiny green alga called desmids. Whereas the diatoms can be found in saltwater, desmids are algae only found in freshwater. Desmids also only appear in green as they contain chlorophyll, a green pigment.

The microscopic cells are divided into halves horizontally, with some having a spiky appearance while others are smooth.

Swimming Algae

Some algae, such as Chlamydomonas, can swim. They are propelled by two flagella, which allow them to swim around. This is another green algae with chlorophyll, which helps it in photosynthesis.

The algae can multiply quickly by swimming around using cell division, a pain for pond owners as the pond can turn green within a few days.

Green algae are often banded together in colonies. Some species may only have a few cells in each colony, while others have thousands. These join to make one individual about the size of a pinhead.

If you have a pond, then there are some little changes you can make to attract more wildlife. Find out more in this article I wrote.


While some algae join in colonies to form a larger individual, others have long mucous-covered filaments. The filaments either attach to the bottom of the pond or float on top. Unfortunately, if this algae covers the entire pond, it can starve the pond of oxygen, effectively killing any other pond and animal life, including fish.

Spring is the best time to see algae on ponds. The light intensity in spring can cause the algae to multiply, and the water can turn green and cloudy.

Do you know what mosses are? Find out in this article I wrote

Blue-Green Algae

Not all algae contain only chlorophyll, with the most primitive algae being bluish-green. Some blue-green algae are the most primitive organisms to live today. These types of algae can be either colonial or filament.

Like other algae, the cells are held together by the cell walls and a jelly substance surrounding them.

These can be found on top of fresh water and attached to the bottom and can sometimes be seen as a slim on rocks.

Find out how to stop skunks digging up your lawn here 


If you have ever been by a pond that smells like rotten eggs, you may have wondered why this smell exists. Unfortunately, the pond is in terrible condition because it has been choked by hydrogen sulfide gas. If the algae have choked the pond, this creates an oxygen-deficient state. Hydrogen sulfide is poisonous, and the pond may take a long time to recover.

Toads leave the safety of water in summer, but where do they go, and what do they do? Find out in this article I wrote