Smart Ways To Kill Out Green Hair Algae In Planted Tank

Long Green Hair Algae Clumps Live On Rocks
Long Green Hair Algae Clumps Live On Rocks (Photo Copyright:

When you wake up in the early morning, you notice a few familiar hairy, stringy green stuff attached to plants in your aquarium. In the beginning, you might not be surprised due to their small number. So, you decide not to take any action to pull them out.

As time passes, they start to multiply their population until becoming a weird fuzzy green carpet, making the aquarium view unsightly. Yes, these strangers are green hair algae; they are a common pest in freshwater and even in saltwater aquarium environments.

Read More

Most green hair algae are not harmful to aquarium inhabitants; they could give some benefits, and even some people let them grow in their tanks. However, most aquarists in the world listed this alga as an outbreak that must be banned due to its ability that can affect the balancing of the ecosystem

A Worst Green Hair Algae Plague
A Worst Green Hair Algae Plague (Photo Copyright:

Actually, green hair algae are not a species; instead, they are a group of green algae plants that consists of several different genera, which also vary in appearance.


What Is Green Hair Algae?

Algae are a member of the kingdom Protista. Like a plant, they could use photosynthesis to produce their own food to continue growing, although they do not have true roots, leaves, or even stems.

A lot of people misunderstand about green hair algae as an individual species that stands alone. In fact, they are a variety of green algae that consists of several distinctive genera. For your information, this hair algae type has four different members, including Oedogonium, Spyrogira, Rhizoclonium, and Cladophora.

All of them have similar characteristics, which are green in color and filamentous or hair-like appearance. Nevertheless, each of them has a typical sign that makes they can be differentiated one and another one.

Green hair algae are the most common scourge of planted tanks; they arise as short green fuzz, and some form long, thin, slimy, and even smell that attach to the substrate, decorations, and live plants. Some also look like tangled green threads floating in the water. It makes them get some nicknames such as fuzz algae, string algae, green thread algae, blanket weed, water silk, mermaid hair, etc. Of course, these names described a particular green hair algae species as their name like.

Not only occupying tropical aquarium environments, but hair algae can also occur in marine or coral tanks as bizarre green fuzzy stuff sticking on some surfaces. They usually start as small green patches, then multiply rapidly, becoming longer hair or dense green mats, making your fish tank unsightly and unhealthy.

A Colony of Small Green Hair Algae Patches Grow On Saltwater Tank Glass Surface
A Colony of Small Green Hair Algae Patches Grow On Saltwater Tank Glass Surface (Photo Copyright:


Is Green Hair Algae Bad For Live Aquatic Plants?

Some plants tolerate the presence of algae if their number is not too much, for example, just a few little clumps at some spots. Both of them can still live together without bothering each other.

However, it will be very different if the algae population begins to grow bigger. Without any attempt to control them, green hair algae would spread faster to almost any space they could reach. In this case, most of your aquatic plants were covered by them, and algae dominated the consumption of carbon dioxide in the water.

Besides that, they also block the light that plants need to grow and use it by themselves for photosynthesis. At this point, you can imagine how suffered the aquatic plants if the green algae take over your aquarium.


Is Green Hair Algae Bad For Fish?

Luckily, green hair algae are harmless for fish and other aquarium inhabitants such as shrimps and snails. For some aquarium fish, green hair algae are one of their favorite snack,s and they will happily munch on them when found attached to plants and decorations.

Some invertebrates and mollusks species also readily feed on some soft green hair algae, especially the young forms and the dead ones.

However, if you leave the hair algae to grow madness, they will turn into thick mats that would cause smaller fish and invertebrates to get entangled, keeping them from eating, even in the worst case, they can die.

In the wild, the longer and stronger hair algae from the spirogyra and cladophora genera could become a nuisance for a few varieties of fish with fewer scales, like Doitsu koi. They are often found having wounds on their skins when inhabiting a pond with rich long hair algae. This can trigger serious issues for fish health.

In the aquarium ecosystem, these algae are prolific and spread quickly to entire corners. While the lighting is on, they consume carbon dioxide, but when it turns off, these algae will begin absorbing the oxygen. Then, thinking if they have large populations in your aquarium, they would lead to a big problem for your fish.

In another case, the infestation of green hair algae can cause ammonia to spike, turning the water cloudy and dirty and causing filters and pumps to be clogged, stopping the nitrogen cycle.


Types, Common Causes, And How To Kill Green Hair Algae

In general, green hair algae varieties are divided into four different genera. Each of them has unique characteristics and appearances that help you distinguish them. Still, they sometimes thrive in the same place and are entangled with each other, making them harder to identify correctly.



This genus is a usual green hair alga group that lives in freshwater environments. They often occur in a tropical tank and are became banned plants by most aquarists.

Oedogonium has holdfast cells that allow them to stick firmly on almost various surfaces. These green hair algae have a fluffy appearance and often arise on a weak or dying aquarium plant.

They usually happen in a mature tank and newer setups. Besides that, the massive trimming of plants’ leaves can stimulate their development.


Oedogonium Algae Characteristic

In the aquarium, their color usually looks ranges from yellow-green to dark green, and the texture does not feel slimy and does not slip on when touched.

Their growth level is faster like another freshwater algal and tends to be prolific in the fish tank with slowing water flow.

A typical feature that Oedogonium could be distinguished from other green hair algal members is the ‘caps’ that are present in some cells. In order to multiply their colony, they can reproduce themselves with three methods, including asexual, sexual, and vegetative.


What Causes Oedogonium Green Hair Algae Appear In The Fish Tank

Generally, there are two main causes that lead this hair alga from this group to grow in the fish tank;

  • Unstable macronutrients. Too-high or too-low phosphates (PO4) and nitrates (NO3) are two substances associated with this pest’s presence.
  • A fluctuation of carbon dioxide content is one of the main reasons for almost freshwater alga thrive in the aquarium, including this one.


How To Kill Oedogonium Algae

You can try several tricks below to kill this green hair alga;

Find out complete information about them and how to get rid of them in this article, ‘Oedogonium algae.’



This green hair algae variety is closely related to the amount of ammonia that is dissolved in the water. So, do not be surprised if your newer aquarium setup has some wrinkled green thread-like stuff because the ammonia substances tend to be higher in this phase. They also can occur in the fish tank with unbalanced water parameters.


Rhizoclonium Algae Characteristic

To find out about this alga species, you should know their characteristics below;

  • Generally, rhizoclonium genera have pale to light green color and often appear as a large, tangled, coarse mat.
  • If you touch them, you will feel much mucus on your fingertip.
  • Their slender filaments can reach up to 2 inches or 5 cm and are not branched.
  • In their habitat, they are often discovered as a floating green mat at the surface rather than to attach to the substrate or an object such as stone or bogwood. While in the aquarium environment, they can colonize almost areas, including growing on the tank floor, sticking on leaves or decorations, and living freely as floating algae.
  • They tend to prefer to thrive in shallow water. Rhizoclonium green hair algae are hardier plants; they can grow in hard water and even in diluted saltwater.


What Causes Rhizoclonium Green Hair Algae Arises In Your Aquarium

Several leading causes that triggered these algae growth are below;

  • A new aquascape tank is prone to invade by this pest due to its unfinished nitrogen cycle, which is the perfect condition for them to live.
  • A poor freshwater tank with low maintenance.
  • Lower carbon dioxide level.
  • Sluggish water flow is also can drive this alga to present.


How To Kill Rhizoclonium Green Hair Algae

Compared with other green hair algae types, the rhizoclonium genera are the easiest to remove; Normally, when the nitrogen cycle has ended, rhizoclonium algae disappear from your tank.

To reduce their population, you can manually remove them using algae cleaner or pick them up using tweezers.

Add some algae eaters such as nerite snails, otocinclus, SAE fish, dwarf shrimps, and Amano shrimps. Some famous small carnivores, such as mollies, guppies, and platies, effectively minimize the algae numbers.

Liquid carbon spot treatments also work like a charm to beat this alga; use 3-5 ml dose daily until the rhizoclonium disappear.

Two Amano ShrimpS Eating Green Hair Algae
Two Amano ShrimpS Eating Green Hair Algae (Photo Copyright: @mamokin on Instagram)



This genus is a stubborn variety of green hair algae family which more than two hundred different species distributed to all parts of the world. Spirogyra is often found in almost freshwater ecosystems; some of them can survive well in the brackish water bodies system.

Spirogyra Characteristic

  • When they appear in the aquarium, this hair algae usually forming as bright green strands.
  • Their body strength is slightly fragile and feels slimy and slippery if you touch them.
  • Sometimes, they can be free-floating stuff and could be forming mimic a brown cotton mat.
  • Spirogyra grows longer rather than rhizoclonium and Oedogonium, reaching up to 6 inches / 15 cm or more in length; they have unbranched filaments.
  • These hair algae reproduce in two ways, sexual (conjugation) and vegetative (cell division). Their multiply rates are faster, and spirogyra can cover all aquarium objects in several days under optimal lighting.
  • Slow-moving water systems are the best condition for them to thrive well.


What Causes Spirogyra Green Hair Algae Thrive

Below are several factors that trigger the infestation of spirogyra in your tropical aquarium;

  • Having too much organic waste from decomposing plants, fish feces, and leftover foods.
  • Over lighting intensity.
  • Lots of micronutrients in the water.
  • Too high phosphorus and nitrogen substances also can stimulate these algae blooming.


How To Kill Spirogyra Green Hair Algae

Most green hair algae commonly need several similar treatment methods, such as;

  • The first step is manual removal, it may not clean all this outbreak. However, it will reduce the algae numbers.
  • Decrease the fertilizer doses until 50% or even stop it because it might become a factor that triggers spirogyra to arise.
  • Some algae eaters like Florida flagfish and Amano shrimp are effective against this alga; they work properly for low-medium outbreak levels.
  • Blackout your tank for three days could become a way to strike them. After that, cut off the daily photoperiod for about two to four hours. Next, you may see these algae turning brown, then pick up the remaining uneaten by the algae eaters.
  • For people that want to achieve fast results, you can use medical treatment methods. Many algaecide brands are offered at the stores that you can try, such as ‘Tetra AlguMin and API Algaefix.’ These products are safe for aquarium fish and plants. Do not forget to read the procedure first on the product labels.
  • Another mighty trick is combining flourish seachem excel and hydrogen peroxide. It needs many efforts due to extreme effects, so it only fits for advanced aquarists. Read the article ‘how to kill spirogyra’ to learn the steps.



Cladophora genera are contained many species that we can categorize into two primary types in the aquarium industry, harmful and beneficial cladophora algae.

The beneficial cladophora like marimo moss balls (C. aegagropila or C. sauteri) often use as decoration in the aquascaping, terrariums, and even paludarium. These varieties are frequently sold at varying prices in local and online aquarium shops.

However, most cladophora species are considered a nuisance and harmful due to their ability that could affect the aquarium ecosystem. Well, any fish tank owner needs to take some action to remove before their infestation goes uncontrolled.


Cladophora Characteristics

Generally, green hair algae under cladophora genera having bright to deep green in a range of colors. They usually release a swampy smell.

If you try to touch them, they will give your fingertips a coarse and springy feel. Dissimilar to most freshwater algae, they do not have a mucilaginous layer, which means cladophora algae are not slimy.

Unlike other green hair algae, they can grow up to 12 inches (30 cm) long when appearing in the aquarium. In comparison, the wild form may reach a few meters.

Furthermore, they can form a dense green mat that is able to stick firmly on the surface of objects or become freely-floating stuff.

Cladophora is a tougher pest; they can develop in slow to faster water flow and live well in cold temperatures.


What Causes Cladophora Algae Grow In Your Aquarium

There are a couple of reasons that might trigger these algae to invade your aquarium;

  • Hitching on new aquarium plants or fish. When you add new marimo moss balls into your tank without bleaching them first, the harmful cladophora spores probably hitchhike on them and wait for a perfect condition to multiply their number.
  • They were introduced from the water in the fish bags. This usually happens to the fish tank in stores contaminated with this outbreak.
  • Slow-flowing water due to a weak filtration system and high lighting is two common mistake that often triggers most aquarium algae, including cladophora.
  • Low carbon dioxide level and imbalance of nutrients in the aquarium. In the outdoor ecosystem, excessive phosphorus levels from lawns or agricultural fertilizers are closely linked to the presence of cladophora algae.
  • Overcrowded aquatic plants make their growth rate slower. In many cases, this creates vegetation underneath going to decay, which is a chance for the algae to establish itself.


How To Kill Cladophora Algae In The Aquarium

Most green hair algae require almost similar methods to eradicate them, of course, cladophora too. Below are several tricks that you can try to fight them off;

  • Removing cladophora algae manually is a great way to eliminate the possible ones. If they grow on decorations, you must pick them up and scrub them thoroughly. While if cladophora forms a mat on the substrate, you should remove part of the substrate because spores might fall there. For any algae that grow on leave plants, you must cut it off in dire cases. Prune the old leaves to prevent their spread in your aquarium.
  • After doing the first step above, adding a couple of algae grazers would have a significant effect. Amano shrimps are an excellent weapon to beat the remains.
  • Injecting CO2 and balancing the nutrients level can speed up the life cycle of cladophora algae, so when they turn yellowish, the algae eaters will start to graze on them.
  • Applying long blackout methods
  • Spot treatment with liquid carbon, such as flourish excel, is proven can push down hair algae growth.
  • Algaecide or algae killer cure also works to destroy them. Some safer medicine for the aquarium population is available in stores such as Algae Clean Out, API Prevent Algae, API AlgaeFix, and Pondcare Algaefix. You can select one and make sure to read the procedure first.
  • Overdosing with hydrogen peroxide treatment may kill cladophora algae quickly. But it is dangerous for all aquarium populations, so we do not suggest trying this method. Adding 1 ml or even more doses for 1 gallon/4,5 liters. Then, you would notice these algae turn pale and die. You can read ‘advised for dealing with cladophora algae’ for complete information about this sucker.
Two Algae Killer Cure For Green Hair Algae, API ALGAEFIX & Fritz Algae Clean Out
Two Algae Killer Cure For Green Hair Algae, API ALGAEFIX & Fritz Algae Clean Out (Photo Copyright: @betta.fishy.kingdom)


How To Prevent Green Hair Algae Invade Your Fish Tank

Performing some activities to prevent infestation of green hair algae is an excellent way rather than medication. Follow these guides below to guard your planted aquarium;

  • Ensure to do regular maintenance. Cleaning your fish tank frequently is necessary to keep the ecosystem stay balanced. Remove any build-up detritus, clean your filter and any submerged equipment primarily, and always check the water parameters as well as aquarium tools’ health.
  • Water change is also part of the maintenance chapter; you can do this while wiping up the fish tank. For low-tech setups without CO2 injection, weekly water change is recommended. It aims to handle harmful contents such as ammonia at a tolerable level.
  • Utilization of high-quality substrate, fertilizers, and RO water is advised. It does not have many nasty substances, including nitrogen, nitrate, ammonia, iron, etc., which is very influential for algae bloom in new tank setups. Ensure to apply that’s all suitable with your tank needed.
  • Only purchase fish, shrimp, snails, and aquatic plants from trusted sellers. Quarantine them before introducing them into your aquarium environment.
  • Remember to feed your pets sufficiently, and never give them too much food. The leftover may be decomposed and then build up on the substrate, while the protein or oil from it would appear on the surface. It will contaminate the water quality and trigger various problems, including these green hair algae groups.
  • Prune the plant’s leaves when they grow too dense. Do not let them grow as they are because when the populations begin to crowd, the underneath plant or leaf is risked and prone to die. The light can not reach them, and there is no space to develop, which causes them hard for photosynthesis.
  • Give your tank enough lighting duration, usually around 7-8 hours daily. Ensure the light levels are appropriate for your aquatic plant types and keep your tank away from direct sunlight.
  • Avoid the dead spots inside the aquarium, and use a compact and high-quality water filtering system. This can drive the fresh water to reach the entire areas in the fish tank.

Related posts