Treating cyanobacteria in freshwater aquariums, seawater and ponds

Cyanobacteria, often wrongly called “blue algae,” are the real bane of many aquarists. These microorganisms, capable of colonizing both fresh and sea water, develop rapidly in unfavorable conditions and can harm the balance of your aquarium or pond. Discover in this article everything you need to know about these organisms, from their identification to their eradication methods, including good prevention practices.

How to recognize cyanobacteria?

Cyanobacteria display bright colors, , especially fluorescent green with blue highlights. They sometimes appear from blue, red, purple, brown, orange or yellow color. . Their texture is viscous or gelatinous. and they give off a nauseating odor. The stench is a mixture of acetone, moldy earth and swamp mud.

Cyanobacteria grow in patches and eventually form a carpet in your aquarium or pond. They trap oxygen bubbles in their slimy agglomerates. Unfortunately, they are difficult to detect at the beginning of their development. However, once they have started to spread, you can no longer miss them!

What are cyanobacteria?

Cyanobacteria — also called blue-green algae — were considered algae until scientists discovered that it was bacteria which they classified with eubacteria. The misunderstanding came from their appearance, but also from their ability to practice photosynthesis, like algae. Cyanobacteria establish themselves in a way at the border between the animal world and the plant world, between bacteria and algae.

The term "cyanobacteria" was chosen because of their cyan color, which is somewhere between blue and green. Cyanobacteria have blue pigments called phycocyanins, as well as red pigments called phycoerythrins that mask the green chlorophyll.

The different genera and species of cyanobacteria

Cyanobacteria are grouped into 130 genera, representing several thousand species. These complex organisms appear indestructible. They have in fact survived all the upheavals of the planet, while animal species succumbed to catastrophes and too radical changes in climate. The oldest traces of cyanobacteria were discovered in Australia in stromatolite rocks dating back more than 3.5 billion years.

Cyanobacteria colonize all environments: fresh water, sea water, oceans, lakes, marshes, polar glaciers, very hot thermal waters. They live scattered in the water and evolve freely, or in benthic form (i.e. at the bottom of the water), attached to the ground.

If the opportunity arises, cyanobacteria use their environment to manufacture their own organic matter. However, in the absence of suitable elements, they manage themselves autonomously using natural or artificial light.

The self-defense system of cyanobacteria

Cyanobacteria have found the best way to defend themselves: They are toxic to fish and other organisms who would like to attack them. Their toxicity is variable, but always present. The cleaning organisms that you can introduce into your aquarium, such as snails for example, will not touch them.

Cyanobacteria irritate the skin, can destroy the nervous system or attack the liver. Some of them are dangerous to humans, causing skin disorders, conjunctivitis and gastroenteritis, among others.

Cyanobacteria proliferation in aquariums and ponds

The inhabitants of your aquarium or pond will not attack cyanobacteria because of their toxicity; they are therefore not at direct risk. On the other hand, Cyanobacteria proliferation affects the flora of your pond. The carpet they form is deposited on the leaves and stems, which suffocates the plants. Because it is deprived of photosynthesis and any chlorophyll activity, the flora loses its vigor, suffocates and dies.

The regeneration speed of cyanobacteria is astonishing. While you have just cleaned your aquarium, the few bacteria that you have not managed to dislodge multiply instantly. In a few hours, they represent a considerable volume, colonizing the bottom and the walls of the pond, in addition to the plants and your decorative accessories.

The causes of the appearance of cyanobacteria in aquariums?

As you will have understood, it appears imperative to prevent the multiplication of cyanobacteria, as they are then difficult to dislodge. They are in reality always present in an aquarium, but they can only trigger their multiplication in the presence of certain factors.

Here are some of the main causes that lead to the appearance of cyanobacteria.

• Imbalance of water, whether fresh or salty.
• Poor pool maintenance.
• Presence of decomposing organic debris on the ground, particularly leaves and plants.
• Insufficient water changes, do withosmosis water of quality.
• Too high temperature, check with a thermometer.
• Water not circulating everywhere in the pool, creating areas of total inactivity. To do this, you can add brewing pumps.
• Cleanings too rare. See our article on theaquarium bottom maintenance.
• Unsuitable or poorly maintained filter. See our article on How to clean your aquarium filter.
• Insufficient mixing, especially on the surface, resulting in a lack of oxygen.
• Food too rich in protein. See our section fish food.
• Food distributed in too large quantities, leaving organic waste.
• Decomposing corpses of a fish that was not evacuated.

Presence of copper in the use of medicines for example. Copper residues kill good bacteria and therefore unbalance the water.

If one of your ponds is colonized by cyanobacteria and you have several aquariums, never use the same tools to maintain them, as you definitely risk contamination of all your pools. On the other hand, remember to wash your hands when you move from one pool to another.

How to eradicate cyanobacteria?

Since cyanobacteria show extraordinary resistance, it is advisable to apply several methods at once to hope to get rid of them.

1) Manual pool maintenance operations

Your first task is to clean the pool. . Remove all visible cyanobacteria by siphoning them off, using a bell jarOr a vacuum cleaner. Cyanobacteria are slimy and gelatinous because they secrete mucilage. When you vacuum up the parasitic mat, you remove most of this slimy substance that helps bind the cyanobacteria together. Of course, you will weaken them, but not completely defeat them.

So be particularly meticulous, because any element you miss is a pretext for new proliferation. Clean all decorative elements, the floor and the walls. Equip yourself with a toothbrush and an algae scraper to help you. See our article onaquarium bottom maintenance

Until you are sure that you have contained the problem, you must commit to more intensive monitoring of your pelvis. You must therefore increase the frequency of:

• water change, withremineralized osmosis water or with salt for sea water. 
• cleaning the pool;
• cleaning filters; See our article onHow to clean your aquarium filter
• water quality monitoring. Thanks tocolorimetric tests or some photometers.

2) The basin blackout

Adjust your lighting quality and intensity. Since cyanobacteria use photosynthesis, depriving them of light hinders their development. You can even put your aquarium in the dark for a few days. Of course, don't overdo it so as not to harm your flora and fauna.

It's necessary at least 4 days of blackout for this technique to take effect. To test this method, you must must not have delicate plants or reef flora who have a vital need for light.

It is also not recommended to repeat the blackout too soon in the event of new proliferation, because you expose yourself to a profound imbalance in your ecosystem.

3) Basin developments

You can add fast growing plants whose aim is to compete with cyanobacteria and bring oxygen to the pond.

It is also recommended to increase the mixing of the water with a more powerful filter or a mixing pump.

Finally, if you can, temporarily remove decorative accessories which constitute as many possible hiding places for cyanobacteria.

4) Water rebalancing

Rebalance the water by adding live bacteria. They can be taken from another healthy aquarium by simply taking a water sample. Otherwise, you can find them in stores.

5) Specific treatments to treat cyanobacteria

If all your attempts toEradicate cyanobacteria have proven unsuccessful, you can resort to specific treatments. . 4 products are particularly suitable for this. They allow you to clean your aquarium, without harming your flora or fauna, whatever it may be: fish, shrimp, snails, corals, etc. On the other hand, these products do not use copper compounds or antibiotics that are now banned. They treat the parasitic algae that you want to get rid of, but do not affect beneficial bacteria which contribute to the balance of the water in your pond.

Treatments may require multiple applications. For each of these four products, we invite you to consult the technical sheet to check their scope of application, in particular whether they are designed for fresh water or sea water. Their dosage and method of application are also specified.

• EASY LIFE - Blue Exit
• EASY LIFE – Excital
• BLUE LIFE USA - Green Cyano Rx
• BLUE LIFE USA - Red Cyano Rx

To help your treatment work faster and more effectively, Siphon off the cyanobacteria present in your aquarium diligently before treating. On the other hand, you must wait the time indicated on the product instructions to see the improvements.

Always remain vigilant in the maintenance of your aquarium and you will have every chance of avoiding the appearance of cyanobacteria.