Thread algae in the pond: Identifying and combating causes
Thread algae in the pond: Identifying and combating causes
Excessive growth of thread algae is not only a visual problem. It can throw the entire pond ecosystem out of balance and even become a deadly trap for some fish.
For this reason, it is important to keep growth under control and prevent the spread of thread algae. In the following we will explain the causes of the strong growth of algae and how you can best combat thread algae in your pond.
What are thread algae?
Filamentous algae are a type of green algae. They are initially tiny and can grow to a length of several metres. With a correspondingly high concentration, the algae can appear in tufts in the pond.
In contrast to so-called floating algae, thread algae attach themselves to the bottom and walls of the pond or to other water plants.
Provided they have enough sun and nutrients at their disposal, they can spread quickly throughout the pond and literally suffocate the other animal and plant inhabitants of the pond.
Thread algae are not always a problem for the pond
Basically, the presence of filamentous algae in the pond is not a problem at first. After all, this is a clear sign that the ecosystem is functioning and that there are sufficient nutrients in the water.
It only becomes problematic when the thread algae take over and the sensitive biological balance in the garden pond is affected. In practice, however, this is very often the case.
Affected pond owners should therefore promptly deal with the causes and find out how to combat thread algae in their garden pond.
Causes of thread algae in the pond
In spring the temperatures slowly but surely rise again. The sun warms up the pond and the nutrient content of the water increases.
Since other water plants and microorganisms are usually not very active at this time of the year, this results in an excess supply of nutrients, which thread algae know how to use. The more phosphate and nitrogen compounds there are in the water, the faster the annoying green algae can spread.
In particular, factors such as direct sunlight, an excessive stocking of fish and too much or even inferior quality fish food can prevent the growth of filamentous algae in the pond even in summer and cause the sensitive ecosystem in the water to become permanently out of balance.
In addition, the following factors can also promote the formation of thread algae in the pond:
- Fertiliser applied near the pond, which is released into the water during rainfall
- Dead water plants that are not removed and release stored nutrients
- Pollen and foliage from the immediate vicinity of the garden pond
- Filling the pond with tap water with a high phosphate content
Possible consequences of thread algae in the garden pond
Excessive growth of thread algae sooner or later leads to numerous problems. Among other things, it causes strong fluctuations in the oxygen content, which can even become life-threatening for the fish in the pond.
In addition, dying filamentous algae, which decompose at the bottom of the pond, damage the water quality and at the same time serve as the basis for the growth of the next generation of algae, so that without manual intervention the problem becomes more and more serious.
In order to keep the ecosystem in your pond permanently in balance, it is therefore important that you combat existing filamentous algae with the right measures and prevent excessive growth.
Fight thread algae in the pond
You should always consider algae destruction only as a short-term solution. These may help temporarily against the thread algae in the pond. However, you will not eliminate the actual cause with them.
In order to effectively combat thread algae in the pond, it’s advisable to deal with the causes and above all to take a look at the water quality.
If, for example, there is an excess of nitrogen compounds and phosphate or a too high pH value, this is a sure sign that you need to take action. It is possible that the location of your garden pond is a problem. Or perhaps you keep too many fish and should therefore reduce the stocking to improve the water quality.
Fight thread algae in your pond with water plants
Aquatic plants can help to reduce the nutrient content in the garden pond and thus remove the basis for excessive growth of filamentous algae.
Floating leaf plants, such as water lilies, are very suitable for this purpose and should cover about half of the area of the garden pond as protection against thread algae. This is because they also provide shade, so that less sunlight is available to the thread algae.
Remove thread algae by hand
Of course, in the case of heavy vegetation, it is hardly sensible to wait until newly introduced aquatic plants take effect.
If necessary, remove the filamentous algae with a rake, a landing net or even a special algae brush. Take care, however, that you do not damage the pond liner or injure any of your fish.
Experience shows that in spring it is necessary to remove thread algae about two to three times a week. In summer, however, it is usually sufficient to take care of it once or twice a month.
High-quality fish food reduces the growth of thread algae
One factor that, although underestimated by many pond owners, can have a major influence on the development of filamentous algae in the garden pond is the quality of the fish food.
Poor-quality food is less digestible and leads to more excretion by your fish. The water quality suffers as a result, which ultimately promotes the formation of thread algae in your pond.
For this reason we recommend that you always pay attention to good quality when buying pond fish food, also in connection with the growth of algae.
With high-quality Koi food from KI-JA-KO or pond fish food from Aquaris you are choosing particularly easily digestible food for your pond inhabitants.
In contrast to many other products, our fish food is characterised among other things by a high bulk density and high-quality ingredients.
You can therefore be sure that you are providing your fish with optimal nutrition and that you are not unnecessarily polluting the water in your pond.
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