My water

Algae in my pond: how do I get rid of them?

In this article, we’ll start by giving you an overview of the types of algae you may encounter in your pond and explain the causes of their appearance. Then we’ll get to the heart of the matter: how to slow their growth and, above all, what you can do to eradicate them. Discover our solutions to get rid of these algae that tarnish the beauty of your pond.

Description of algae

Algae are living creatures, plants that combine water and carbon dioxide to form sugars for energy and growth through photosynthesis. Most of their life cycle takes place in an aquatic environment. They also represent a major part of biodiversity. They have no roots, stems, flowers or leaves. They are unpleasant to the eye, preventing you from fully contemplating the aquatic life in your pond, but they are also smelly and a real hindrance to the serene swimming of your fish.

Generally speaking, algae appear and develop when the water in the pond is clear and there is plenty of light. Even in winter, it’s not unusual to see a sudden increase in algae in your pond after a sunny day. This is because algae take advantage of the vegetative rest of your aquatic plants to feed on nutrients in the water that have not been absorbed. Furthermore, when the water is heavily loaded with unabsorbed organic matter, this will also encourage algae proliferation.

During the day, algae produce oxygen from sunlight. At night, they release carbon dioxide, which depletes the oxygen in the pond. There are different types of algae, which can be classified into different categories, notably by colour: blue-green, brown, green and red. In this article, we will be focusing mainly on green algae, but here is a parenthesis on blue algae, which mainly bloom during heatwaves.

Blue-green algae: bacteria that are toxic to living beings

The presence of blue-green algae is the result of hot summer weather. These algae can release toxins into the water and are dangerous to public health. Cyanobacteria, also known as ‘blue-green algae’, thrive particularly in hot, sunny conditions.

These bacteria are harmful and toxic to humans, and can lead to skin and throat irritation, headaches, and even digestive issues. Be especially careful with pets thjat might try to drink from contaminated water, as it could be fatal for them. So take care and follow any restrictions in place to protect your health when swimming in natural bodies of water.

2 types of pond green algae

A. Filamentous algae

Filamentous algae (or hair algae) are, as their name suggests, filament- (or hair-) shaped and slimy. These long green filaments cling to walls, rocks and waterfalls. As they grow, they become tangled and detached, eventually turning into thick, slippery yellow-brown-green mats that float on the water surface.

Often, when you have filamentous algae, the water is also clear. Their presence indicates high levels of phosphates and nitrates. They feed mainly on these to proliferate.

B. Green water

These algae are single-celled organisms, invisible to the naked eye. They are so tiny that they can pass through even the finest filters. Their main characteristic is that they remain suspended in the water. If all the right conditions are met in terms of light and nutrients present in the water, they can multiply up to 5 million algae cells per ml of water.

What causes algae to appear?

Various factors can lead to the appearance and growth of algae:

The quality of the water (hardness toop low, pH too high, the level of phosphates, nitrates, etc.).
The filtration system, the sizing of which should be checked to ensure it is suited to the volume of the pond and the number of fish.
Too much organic matter at the bottom of the pond.
Overpopulation of fish.
Overfeeding of fish or use of lower-quality food.
Too few or no aquatic plants (and therefore high phosphate levels).

Green water and filamentous algae are particularly common in the spring and summer months. It’s important to remember, however, that the appearance of green water is a normal and natural phenomenon.

Introducing aquatic plants such as cattails, water lilies or watercress into the pond will help to absorb the nutrients present in the water. These plants will therefore play their purification role, which partially neutralises the growth of algae. However, if you don’t have aquatic plants, you’ll need to opt for an anti-phosphate solution to limit the appearance of filamentous algae.

In addition, a UV clarification system should be installed to clear the water, neutralise microalgae and eliminate green water.

What are the solutions to get rid of algae?

The first step, and the one that should be our first reflex, is to measure the parameters of your water. It’s crucial to always start by analysing your pond water. Why should you do this? Because treating pond water by ‘randomly throwing’ products into the water is in no way beneficial. It’s important to look at the results after measuring the water so that you can react appropriately.

It is precisely these unbalanced and unstable water parameters that can be responsible for the appearance of algae and cloudy water (opaque, misty or muddy appearance of the water).

Bear in mind that an algae treatment is fast-acting. However, the effects are mainly short-term (a few months) and will not prevent the return of unsightly algae. It’s a good idea, therefore, to sit down and look at any underlying problems. Taking the time to understand how the water and your pond work is essential if you are to avoid an invasion of algae (and other inconveniences). Having a pond at home is more than just an aesthetic distraction; you should always be aware that you are in a way acting as guarantor of a small ecosystem that needs to be looked after.

By being proactive and favouring preventive solutions, you can save yourself a lot of trouble.

What should you remember to avoid algae?

Ensure that your water is well-balanced by regularly analysing its parameters.
Install a filtration system suited to the volume of your pond and the number of fish. Clean it monthly.
Oxygenate your pond to keep the water constantly moving and prevent algae growth.
Opt for a UV steriliser.
Have the right proportion of aquatic plants (or use an anti-phosphate agent if there are no aquatic plants).
Feed your fish reasonably, in small quantities several times a day and with quality food.

Solutions for silt, algae and organic waste.

Biobooster+ is a formulation designed to boost the activity of the micro-organisms that benefit ponds. The effect on organic waste is visible after just a few minutes. It then boosts the development of bacteria, leading to the elimination of waste. Biobooster+ contains no products that are harmful to filtration, the environment or the fish, which emerge from this pond treatment stronger and healthier.

Bactogen is a concentrated blend of bacteria, enzymes, minerals and trace elements. It is recommended for biological filtration maintenance throughout most of the year. It also improves the biological quality of the water and the purification cycle for organic pollutants.

The role of bacteria.

Bacteria are useful for digesting nutrients in the water and controlling the organic load. They help to combat siltation and algae, while promoting good filtration. They therefore play an active role in maintaining the quality and balance of your pond water.

Mineralise, clean and maintain are the 3 steps you need to take to ensure that your fish and pond are in ‘good health’.