3 Types of Pond Algae – And How to Get Rid of Them

Algae is a name that encompasses a large, diverse group of organisms that occurs in most water habitats – as well as the problems associated with these organisms. Algae is an important component of the nitrogen cycle and is completely natural. It’s part of nature’s way creating balance in your pond.

Algae also processes waste and organics, because the end product of nitrates and phosphates serve as food for the organisms. Sunlight contributes to an increase of algae as well, because it is photosynthetic. A combination of sunlight and high nitrate content equates to more algae.

Why Pond Owners Dislike Algae

While algae growth does not necessarily indicate an unhealthy pond, many pond owners find it to be aesthetically unappealing. A pond tinged with green can definitely be an eyesore, especially when it masks the view of fish and other aquatic plants and makes it difficult to enjoy the pond overall.

Types of Algae

Not all algae is created equal. The three most common types of algae are free-floating algae, string algae, and the light, sometimes fuzzy algae most commonly seen on rocks in the pond.

1. Free-floating or Planktonic Algae

This algae can make the water fully green, giving it a sort of “pea soup” texture. The pond will appear stale; a thick, soupy pond is also undesirable because it makes it difficult to see fish and other pond life.

Free-Floating Algae

2. String algae

Also called filamentous algae, is the long, stringy substance that attaches to rocks in the pond and to those in a waterfall. Pond owners often dislike string algae because it makes a pond undesirable to look at, giving it a swampy appearance.

Hair Algae

3. The Green, Fuzzy Algae

This that occurs on rocks in the pond or in the waterfall is highly common. This type of algae is actually present in most healthy ponds, and does not necessarily need to be eliminated, as it doesn’t compromise the health of the pond. However, some pond owners still dislike this kind of algae and want to get rid of it, which is possible to do without harming the health of the pond.

Light Algae on Rocks

Inhibiting Algae Growth

Algae will naturally occur wherever the is adequate food and light. Pond owners can naturally and organically inhibit algae growth by using competing plants and bacteria, as well as by diminishing the amount of light that reaches the pond.

For example, if the pond has yet to be installed, it can be positioned in such a way that it is not directly lit all the time, which lessens algae production. Pond owners can also plant lily pads to provide cover from light. An additional benefit of lily pads is that these plants consume nutrients in the pond that would otherwise go to algae.

Another way to reduce the amount of light that penetrates the pond is to tint the water blue or brown. While many pond owners dislike the idea of changing the natural color of the water, a blue tint will actually complement fish like koi that are bright red, white, or orange, making them stand out better.

Natural Algae Growth Inhibitors

Many pond owners have probably heard that barley is a way to inhibit algae growth. When barley decomposes, it produces an enzyme that keeps algae from blooming. Pond owners can place barley pellets in stagnant areas of the pond to naturally prevent algae growth. Another option is to use concentrated barley extract.

Introducing beneficial bacteria is another way to help get rid of algae. By creating a large surface area for bacteria to colonize, pond owners can prevent algae from growing further. One product that helps bacteria grow more readily is our own Laguna BioMax, which provides massive surface area for bacteria to colonize. One litre of this product provides more than 15,000 square feet of surface area for bacterial colonization. Pond owners can speed this growth process along by providing adequate circulation in the pond, which enhances oxygenation of the water and encourages bacteria growth.

Other Algae Growth Solutions

String algae can often appear during late spring months in Canada and the northernmost United States. It is possible to “catch up” with this kind of algae by manually pulling it off rocks, however, this can prove to be labour intensive and there are products that can assist with this process. EcoBlast, a product available from Aquascape, is a granular product designed to eliminate algae from streams, waterfalls, and fountains. This product is best applied directly to algae, so pond owners can sprinkle EcoBlast over problematic parts of the pond. Once the algae is released from rocks, it can be scooped up with a net or removed through the pond’s filtration system.

Another effective (long-term) solution is the IonGen, an electronic pond clarifier. This solution consists of a silver and copper probe that slightly improves the copper content of the pond, which makes it unpalatable for algae. IonGen does require the pond’s alkalinity to fall between 100 and 250 parts per million, but it is simple to manage the water content so that it remains within this range. Pond owners who don’t want any algae at all can use this product to completely eliminate growth, while still allowing other plants to thrive. 

It is also possible to eliminate free-floating algae with the use of a UV sterilizer or a pressurized filter with a UV light. By running water through the filter and exposing it to UV light, anything free-floating will be killed off, including algae and parasites. This solution will completely eliminate any free-floating organisms and doesn’t harm the pond. Utilizing a sterilizer light does require good flow and a current UV bulb, with the life expectancy of the bulb being roughly 6 months. While a bulb past that time frame will still light, it will no longer be effective as an algae inhibitor.

With all of these solutions, it’s always important to remember that proper pond maintenance, filtration, and care are some of the most essential components of controlling algae growth.