7 Tips To Fight Cyano Successfully


This is how to fight Cyano in the saltwater aquarium

Cyano is a photosynthesizing bacterium that produces cyanotoxins and discolors the water in the aquarium. Cyanobacterial cells may be found at the water surface, at a defined depth, or present throughout the water column.

Cyanobacteria form red or green mat-like coatings that can completely cover both the substrate and the stone structures in your aquarium in the event of very severe infestation. They do not stop at corals and other stuck organisms. But it doesn’t have to come to that. If you act early, you will soon get the problem under control again.

This article gives you 7 tips on how you can combat the cyano deposits:

Cyano in the Aquarium

# 1 Vacuum cyano debris regularly

If cyanobacteria have already spread in your aquarium, you should try to repeatedly vacuum off the reddish deposits. You must dispose of the resulting ‘wastewater’! 

To avoid losing too much tank water, use the thinnest possible hose. It can take a while before vacuuming the plaque regularly has an effect. 


  • Buy a tiny vacuum that will perfectly get the cyano off the sand.
  • Make sure that you such out some of the infected sand when vacuuming
  • You can also take this time to use baster and clean all the rocks.

# 2 Bacteria versus cyanos

Cyanobacteria are particularly common in aquariums that are biologically unstable. 

What does biologically unstable mean? – Biologically unstable means that a functioning bacterial community does not yet exist. Many “good” bacteria in your aquarium compete with the cyanobacteria and thus limit their development. 

It is a good idea to use of live rock or special bacterial solutions such as nitribiotic. They are beneficial here. The addition of bacterial solutions is particularly effective if you inject them directly into the substrate with the help of a syringe and a cannula.

How do bacteria help with Cyano?

There are effective strains of Bacteria that either eat or compete with cyano. You can just add a dose of probiotic bacteria to exhaust the food sources that the Cyano is dining on. Regular dosing of bacteria will help to prevent or fight cyanobacteria.

# 3 Phytoplankton versus cyanobacteria

Similar to the use of bacteria, phytoplankton can also compete with Cyanos and curb the spread of the deposits. Living phytoplankton of the genus Synechococcus sp. (Incidentally, a cyanobacteria itself, which does not form any deposits and is “good” for tank biology) proved to be particularly effective.

# 4 Avoid “sticky corners”

Cyanobacteria love “rotten corners” and therefore prefer to occur in places where a lot of sludge is deposited due to weak or no current. It can already help to improve the flow pattern in your pool. Try to realign your pumps or increase their performance a little. If this is not possible, you can consider using additional pumps or exchanging them for more powerful pumps. Furthermore, you should remove sludge from the substrate in your tank at regular intervals. It is best to use a sludge bell for this.

# 5 Check and optimize your water values

A wide variety of parameters can promote the growth of cyanobacteria. Some cyano species benefit when no nutrients are detectable in the water. Still other species have the ability to take up molecular nitrogen from the environment and fix it in the form of ammonium. In the case of a nitrogen deficiency and a simultaneous excess of phosphate, such cyanobacteria get a real advantage. Therefore, pay attention to a balanced nitrate: phosphate ratio (ideally 1: 100) and if necessary raise the nutrients a little above the detection limit. Increased phosphate concentrations can be reduced by using a phosphate adsorber.

# 6 Supportive measures

Avoid using a carbon dosage (e.g. vodka method, products with ethanol or sugars as ingredients) while the cyano problem exists, as these generally promote bacterial growth (including that of cyanobacteria). In addition, you should temporarily stop the addition of trace elements and amino acids. An additional filter through activated carbon can be useful to remove possible toxins of the cyanobacteria. In addition, check your silicate content in the water again and take measures if necessary (e.g. renewing the mixed-bed resin of the osmosis system) to remove silicate.

# 7 The last resort of choice

If you have taken all of the measures listed here, but have not improved after several weeks, you can think about using an anticyano preparation. Trading offers you numerous options here. However, you should make sure that the preparation does not contain any antibiotics. Since pelvic biology is often badly affected by the use of these remedies, they should be viewed as the last option. Should you still decide to do so, it is advisable to stabilize the pelvic biology by adding a bacterial solution after the treatment.

How to get rid of Cyanobacteria

Frequently Asked Questions (FAQs) on Cyano

What causes Cyanobacteria?

Cyano forms a thin layer of debris or detritus on the substrate and uses it a nutrient source. Common causes are:

• Nitrates and phosphates fuel cyanobacterial growth,
• The “slime algae” can also seem to grow when dosed with a carbon source which is ultimately used lower nitrates and phosphates and kill cyano.
• It can be introduced on rock, corals or macroalgae
• At times it can also appear in tanks that were sterile meaning is may even be airbourne.

How do I treat cyanobacteria?

Other that the tips listed above you can also:

• Improve mechanical filtration to remove particles from the water. Fewer particles mean less settlement, and cyano tends to grow over patches of dirt.
• Increase the aquarium flow by upgrading or adding more wavemaking pumps, and setting them to pulse mode can help to tear the sheets of bacteria off rocks and substrate.
• Create a strong gyre growth to help keep the cyano particles in suspension.
• Test water to ensure that the Redfield ratio is stable.

Can bacteria eat Cyanobacteria?

There are effective strains of Bacteria that either eat or compete with cyano. You can just add a dose of probiotic bacteria to exhaust the food sources that the Cyano is dining on. Regular dosing of bacteria will help to prevent or fight cyanobacteria.

Can you cure cyanobacteria with a blackout?

A blackout involves turning off the tank lights and completely sealing it in black material to not allow any light into the tank.
Because cyano is photosynthetic; the lack of light means that the cyano will shrink, die, and disappear. This does not affect other freshwater plants since they can cope with a few days of total black out, and survive.
You have to remember that blackouts are only cosmetic fix. They do not address the root cause of the cyano.

Are cyano the same as diatoms?

Diatoms are also slimy and cause sheets of brown slime, especially on new rocks and sand and in new tanks. Diatoms have structures made from silicates, so RO/DI systems with silicate removal capabilities and phosphate removers that also remove silicates are one way to tackle them.

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