In total there are several thousand types of algae so that not only one type of algae can usually be found in Koi ponds. This wide variety of species means that there is no “right” way to solve an algae problem in the Koi pond. 

A few years ago, chemical agents were used to combat algae, some of the ingredients of which have now been banned by law. These agents were not only dangerous for the fish living in the pond, but they also only combated the symptoms of the algae problem – i.e. the algae growth – but not its causes.

In order to be able to grow and survive in a body of water, algae primarily need phosphate.

This gets into the water in various ways. For example, some fish feed contains phosphate as a binding agent. Inferior food is particularly often high in phosphate, so you should use high-quality food to avoid algae problems. Phosphate can also get into the pond via commercially available pre-fertilized pond soil or garden soil.

If you use special quartz gravel for planting, you can avoid an algae problem in this way. Furthermore, leaves from bushes and trees can lead to the formation of algae. In the water, the leaves release a lot of phosphates and also trigger putrefaction processes. For this reason, leaves should always be removed from the pond.

A lot of phosphate gets into the pond even if there are pollen-shedding trees or flower beds nearby – pollen also contains a lot of phosphates. In addition, rain can promote the growth of algae, because together with the rainwater, nutrients from the area around the pond enter the water. 

Therefore, the pond should be built in such a way that no water from the environment can run into it.

Read our article on Green Pond Water here.