Algae is a type of plant that typically thrives in wet or damp environments. This includes garden ponds. If you are having trouble with algae in your pond, there are several steps that you can take to prevent it from coming back. The first step is to make sure that the water level stays low enough for sunlight to reach the bottom of the pond and kill any algae on the surface. You should also periodically skim off any algae sitting at the top of your pond, otherwise, it will continue to grow and spread throughout your entire body of water!
At first, algae are no cause for major concern; on the contrary, they are an important component of the pond’s mini-ecosystem and are evidence of good water quality. However, pond owners should keep a close eye on them and take countermeasures if they proliferate.
Distinguish filamentous algae and suspended algae
There are two different types of algae to distinguish: The greenish slimy islands on the water surface are usually the filaments of filamentous algae.
Floating algae, on the other hand, are very small and float through the water. If they multiply strongly, the water turns greenish.
Fight algae naturally
If you want to drive back algae, you can compete with them by using other water plants. The more aquatic plants in the pond, the fewer nutrients the algae can use for their growth. About one-third of the pond surface should be covered with vegetation. Good services are provided by proliferating floating plants such as duckweed or crayfish.
Since algae, like all plants, require light, it is also advisable to use plants that shade the water surface. Water lily, lotus, sea port, and frogbit are well suited. A small fountain, which provides constant water movement further disturbs algae growth. Aquatic rake can be used if you want to take care of business quickly.
Suspended algae: Cloudy water in spring
Suspended algae usually appear more frequently in spring, when the other water plants are not yet as large after the winter. They can be kept in check well with water fleas, which are available at aquarium supply stores. The little critters feed on the algae. By about mid-May, they have almost completely eaten the floating layers. Then the water fleas die and sink to the bottom. The visual turbidity has disappeared and the water in the pond is almost clear again, although slight turbidity is quite normal.
Remove thread algae regularly
If filamentous algae grow in the pond, this initially speaks for the biological quality of the pond. They provide oxygen and are both food and a hiding place for small creatures such as tadpoles. Nevertheless, they should be removed regularly because they sink to the bottom of the pond when they die, release nutrients into the pond and at the same time deprive the pond of so much oxygen when they decompose that, in the worst case, fish and other creatures suffocate. This condition is called the overturning of the pond.
Fish out with algae landing net
To prevent this, it is best to remove all algae that can be easily detached every two to three days starting in mid-April. In June and July, it is sufficient to carry out the procedure every three to four weeks. It is best to fish out the algae with a special algae net. Alternatively, they can also be easily “wound out” with a thick branch, similar to spaghetti on a fork. This method is particularly suitable if there is a risk of accidentally pulling other aquatic plants out of the water with them. Do not use coarse prong rakes to catch algae: The tines could damage the pond liner. The algae fished out can be disposed of in the compost without any problems.
Prevent excessive algae formation
To prevent algae from forming in the first place, pond lovers should ensure that as few additional nutrients as possible enter the pond, such as excess fish food or lawn fertilizer washed in by the rain. Falling leaves also bring unwanted additional nutrients. This can be remedied by stretching a net over the pond in the fall to keep the leaves out of the water.
A stable oak branch placed in the water also lowers the pH value by releasing its tannic acid. This worsens the living conditions of the algae. However, you must remove the branch before it decomposes, otherwise, the process is reversed.