If a green coating forms in the pond or numerous free-floating algae appear in the aquarium, it is floating algae. Fighting these sustainably is difficult for many owners, as they multiply quickly and incessantly. Over time, they cause a lack of oxygen and cloudiness in the water, which has a significant impact on the quality of life of plants and animals.
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Causes of floating algae
Suspended algae in your pond or aquarium are a bigger problem than you might think. These are either eyelash ball algae (Volvox), which are greenish, or bacteria, which are white in color. Thread algae can also be the cause. Fast reproduction is typical for all organisms, as they can multiply suddenly within a short period of time and lead to considerable problems in the long run:
- Water becomes cloudy
- Oxygen plants no longer receive any light
- Oxygen concentration decreases dangerously
- Animals and plants suffocate
These algae are often found in the first time after setting up an aquarium or completing a garden pond. Since at this point the plants, animals and other microorganisms have not yet ensured a balance in the water, it is easy for the algae to multiply. For this reason, you have to pay particular attention to whether the water turns green and does not become clearer even with a high-quality filter system. In this case, you need to do something. The following causes can also prevail:
- excessive exposure to sunlight
- too few predators
- stale water
- Nutrient excess
Algae benefit from an excess of nutrients. For this reason, even heavy rainfall can affect the formation of algae if this soil with many nutrients enters the pond and the content is thus significantly increased. Another cause of the excess nutrients can be the pond inhabitants:
- too many fish
- lots of big fish
- fish food not consumed
Why are fish responsible for the development of algae? The excretions of fish contain phosphates, which support a high supply of nutrients and often over-enrich the water with them. Large fish such as koi in particular cause high levels of phosphate. You should also refrain from overfeeding your pond inhabitants. If a large part of the feed is not consumed, it sinks to the bottom and creates an excess of phosphate. This is not so problematic in aquariums, and even less so in saltwater aquariums, since floating algae occur mainly in freshwater. If you want to keep many or large fish, you should always have a good filter system.
Sustainable removal of floating algae: 7 methods
As soon as you have identified floating algae, you must use appropriate methods to combat them and remove them sustainably. It is important to check the above causes before attempting any of the solutions below. You don’t want to buy a cover for your aquarium as sun protection because you are feeding your fish too much. So check the conditions and try one of the seven methods that help against the floating algae and ensure clear water.
Skim off floating algae
As simple as this method may sound, fishing the algae can help in some cases, especially if an aquarium is still in the acclimatization phase or the garden pond has only just been completed. At this point it is important to remove these and thus reduce their reproduction. This method is just as important in autumn, when leaves, pollen and other organic materials collect on the surface of the water. If the sun is still very strong, the algae have an easy time of it. This method is particularly easy to use in the aquarium.
Aquatic plants
The use of aquatic plants, which require high amounts of nitrate and phosphate, ensures natural control of the algae. Include this in the fauna of the water and within a short time the water will clear. You can find a small selection here:
- Hornkraut (bot. Ceratophyllum demersum)
- Waterweed (bot. Elodea)
- Milfoil (bot. Myriophyllum)
- Reed (bot.Phragmites australis)
- Tube flasks (bot. Typha)
- Water vapor (bot. Glyceria maxima)
As soon as these take over, remove the excess growth. The advantage: the nutrients are stored by the plant and are removed from the water along with it.
Darken
During the summer it is typical to discover an infestation by floating algae. If you want to fight this, you have to shut out the warming light and thus deprive the algae of the basis of life. While this can only be achieved with partially shaded locations and a water change in garden ponds, you have to proceed as follows with aquariums:
- Feed the fish in the morning
- change the water
- 50 to 70 percent of the water
- darken the aquarium
- Turn off the lights
- Stop feeding fish
- this condition remains for three to five days
- Turn on the light and remove the cover
- Carry out a water change
- clean filter
Replace substrate
Since soil often contains nutrients that are released into the water and thus promote the formation of algae, you should think about changing the substrate. While gravel or sand, which belong to the nutrient-poor substrates, are often used in the aquarium, you should definitely replace the pond soil. Of course, you have to completely drain the pond, clean it and fill it with new substrate, but algae formation on gravel and sand is hardly possible. Especially if you use a filter system and a sludge extractor, the floating algae no longer have a basis for their spread.
UV clarifier
A UV clarifier can be used in ponds and aquariums. The device emits UV rays, which make the algae incapable and thus disrupt their behavior. They cannot reproduce any further and will decompose over time. The UV clarifier should only be used until the floating algae have been removed, as other important microorganisms are also rendered incapable by the UV rays. As soon as the water is clear again, pack the device up.
Water change and cleaning
As mentioned above when replacing the substrate, you should change 65 to 70 percent of the water at regular intervals to prevent the algae. Alternatively, you can clean the pond or water in a set rhythm. Above all, you can get too many nutrients out of the water. If there is an explosive algae infestation, proceed as follows:
- Change 90 percent of the water
- over a period of several days in a row
- Repeat until all floating algae have disappeared
Although this method is laborious, you don’t have to change all of the water in the pond. The daily fresh water does this for you.
Predators
Algae are organisms that provide nutritious food for a wide variety of animals. For this reason, you should establish appropriate predators that can feast on them:
- Hopscotch
- Water fleas
Conclusion
Floating algae is not to be trifled with. The organisms reduce the oxygen content in the pond or aquarium and must be combated. Especially in the early days after building a pond or setting up an aquarium, it is necessary to prevent them from settling. This is not a problem with suitable methods.
