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Common Algae Issue in Planted Tanks

What are the most common algae in a planted tank and how to solve them?

First of all, when algae first appears in your planted tank, don’t panic or disappoint. The appearance of algae shows that all aspects of your tank are suitable for plant growth, otherwise algae won’t grow as algae is also one of the common green plants on the earth, but when it grows too much, covering the surface of the aquatic plants, it definitely causes a big problem, such as plants’ non-growth, shortness, and no color development.

Why do they appear?

The appearance of most of the algae indicates that there are too many nutrients and too much light in this tank that the plant can not absorb completely. These excessive nutrients and light nourish the algae spores in the water and make them start to grow. 

Therefore, by changing the water more frequently, avoiding overfeeding, stopping fertilizing and reducing the light, the algae problem can be effectively controlled, under a safe level.

Now let's look at some common algae in planted tanks and learn how to control it efficiently.

#1 - Brown Algae

Brown algae problem mainly appears in the initial stage (within first three months) of a new tank scaped. When it shows up, it may cause many fishes and shrimps to die and make a huge loss for new aquascapers.

Brown Algae

Common locations - On the walls of the tank and the surface of driftwood, stones, etc.

Cause - The main reason is that the biofiltration of the tank has not been established or perfected. Once it establishes, normally this kind of algae will gradually disappear. 

Solution - Speed ​​up the establishment of the biofiltration system by adding into high-quality freshwater filtration bacteria during the start-up stage or putting a used filtration pads, which is unwashed from an old tank where biofiltration has been established, into this new filter canister. All of these can help build the biofiltration system as quickly as possible. Those tiny invisible beneficial bacteria can help decompose excessive nutrients such as ammonia and nitrite in water, preventing brown algae’s growth.

#2 Hair Algae

It usually takes roots on needle-like aquatic plants, such as moss. Even it looks messy but its appearance proves the stability of water quality that fishes and shrimps are not easily going to die. Now, Lets see how to control hair algae.

Hair Algae

Cause -

  • Too much light with limited aquatic plants in water.
  • Excessive nutrition in water.


  • Reduce the light intensity or time and reduce dozing any fertilizer.
  • Use a toothbrush to brush off those hair algae.
  • Add more little algae-eating creatures into the tank, such as Amano Shrimp, Dwarf Sucker fish and etc.

#3 Blue Algae - Cyanobacteria 

From the name, you can tell that this“Blue Algae”is caused by growth of cyanobacteria, which likes to grow moist soils and water. 

The color of Cyanobacteria algae is blue, green or black, covering the surface of the bottom sand. It is slimy and with a very strong fishy odor.

Location - frequently appear on the bottom sand or corners between bottom and walls.

Cause -

  • Water hardness is too high, high levels of dissolved wastes in water that provide a good food source for this bacteria.
  • Substrate or sand is too fine that  provides a good environment for Cyanobacteria to grow.

Solution -

  • Remove those algae by using a gravel vacuum cleaner, deeply clean the sand or gravel. 
  • Keep changing water frequently to reduce the nutrients in water.

#4 Green Water

Many new aquascapers may have this experience. In the beginning, tank water is clear and transparent, suddenly it becomes misty green and invisible, and gradually turns into dark green, which is called “green water”.

green water

Causes -

  • Extensive and strong lighting, like sunlight, causes tiny green algae to grow rapidly in water.
  •  Insufficient filtration

Solution -

  • Reduce light for a while.
  • Need a powerful filtration  -clean the filter pads or add a UV sterilizer in the filtration system which can kill the algae spore easily without any damage to the fishes or shrimps.
  • Change water frequently.

#5 Green Spot Algae

It is very common in freshwater aquariums and most aquascapers have to solve it frequently. It is named for what it looks like - small, round, green spots. Unlike most other algae, this type of algae does not grow tall but almost flat and hard to the touch.

Locations - Tank walls, leaves of the slow-growing plants, such as ANUBIAS NANA PETITE or other broad leaves plants.

Causes - Extensive and strong lighting

Solution -

  • Use biological treatment by adding more little algae-eating creatures into the tank, such as Nerite Snail and Mystery Apple Snail.
  • Regularly scrub to clean the tank wall.
  • Remove the affected leaves with green spot algae, and adjust the layout of the tank by moving the plants that are prone to get this algae to another new location.

#6 Rhizoclonium algae

It looks similar to Hair algae but actually it is different. It is more likely to grow in moss clumps or on the roots area of hairgrass (Eleocharis parvula) with a form of clusters of filamentous shape

Causes - A lack of general maintenance, low nutrients, low CO2, and poor water circulation.

Solution -

  • Use a toothbrush to brush off those algae and check the water circulation and CO2 levels. Once the nitrogen cycle is restored or finished, Rhizoclonium often disappears
  • Please note that algae eaters, shrimps or fishes are not able to eat this kind of algae.

#7 Black Bearded algae/black brush algae

As it is named, it looks like - a black algae that looks like a scruffy beard, also named black brush algae.

It is the most difficult to deal with this kind of algae. Once it appears and expands, it greatly affects the overall appearance of your tank and needs to be removed as soon as possible.

Locations - surface of wood, filter’s inlet and outlet, bottom sand, plants’ leaves, etc.


  • High PH level and high hardness of the water.
  • Too much  bait residual left in tank
  • Too many fishes.
  • The composition of the liquid fertilizer added to the tank is imbalanced, resulting in an imbalance of nutrient elements.
  • Low-quality base/root fertilizer
  • No frequent water changing, leading to accumulation of nutrients
  • Insufficient and poor filtering capacity

Solution -

Try to solve it at the earliest stage if you find it.

  • Add more algae eaters, such as Siamese fish, Otocinclus Dwarf suckers into the tank. Choose the smaller ones instead of big ones who are unwilling to “work” on eating algae.
  • Improve the water quality. Either add CO2 levels to balance the high PH water or add soft water inside whose PH level is around 6.5 and PH level is around 8.
  • Don't add too many variants of fish into a planted tank, only keep those small fishes that fit in a planted tank.
  • Stop using poor fertilizer and improve the water quality by enhancing the filtering capacity.

# 8 Staghorn Algae/Bartalgen

Its appearance is grey-green color and its shape is like hair or antlers of a male deer. It is easily confused with Black bearded algae but it is different. Fully grown black beard algae is dense and bushy while staghorn algae, on the opposite, is sparse and wiry.

Locations - Edges of plants leaves.

Causes - High levels of Ammonia and Nitrogen in water. High PH level in water.

Solution -

  •  Remove the affected leaves and get rid of all of the algae.
  • Reduce the frequency of feeding fishes. Reduce the varieties of fishes.
  • Improve the water quality. Either add CO2 levels to balance the high PH water or add soft water inside whose PH level is around 6.5 and PH level is around 8.

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