How to Remove Hair Algae in Aquariums

How to Remove Hair Algae in Aquariums

How to remove algae, and hair algae in particular, is one of the most common problems in the aquarium hobby. Algae has been the bane of our existence since … forever! Even though every year we gain more knowledge and get some new, fantastic products that can help us in this battle, it is still not enough.

Hair algae usually form long wispy threads up to 20 cm. If left untreated, algae can grow fairly quickly and take over a tank within a few weeks or even days. Although Hair algae are considered, mistakenly, more like a nuisance, it can still clog filters, pumps and even crash the nitrogen cycle.  

Hair algae are not just one genus or species of algae, as some articles state. These algae include several genera, where the most common are Rhizoclonium, Cladophora, Spirogyra, Oedogonium.

In this article, you will know different types of Hair algae, what causes them and, what is more important, how to get rid of them or prevent their appearance in the tank.

Are Hair Algae Harmful to Plants and Animals?

Yes, hair algae can be harmful to the plants when it starts getting bad. For example,

  • Algae compete with plants for nutrients (Allelopathy) and can stunt their growth.
  • When hair algae cover the plants, the plants cannot perform photosynthesis and grow accordingly. In the worst-case scenario, the plant will simply die.
  • In a heavily infested tank, when hair algae die, they can cause ammonia spikes. These substances are very toxic to fish and shrimp. High concentrations can wipe out your whole tank.
  • Some hair algae species can be so long that small fish and fry can entangle in it and die.
  • Sometimes there can be so much algae on the plant that the only way to get rid of it – remove the whole plants with the algae.
  • Water becomes dirty and cloudy.
  • Algae can slow down gas exchanges in the tank that will slow the plants’ growth as well.
  • Reduction in invertebrate densities and fish spawning.
  • Can clog filters, pumps, and crash the nitrogen cycle.

Even though, it may not be a problem in the beginning, when it starts getting bad (and it will turn ugly very quickly!), hair algae can be very harmful to plants and animals in the tanks.

Types of Hair algae

1. Rhizoclonium

Rhizoclonium Hair algae in aquariumsThese nuisance hair algae usually show up in recently launched or heavily unbalanced aquarium systems. Therefore, when there is a significant amount of ammonia in the tank, you should not be surprised if Rhizoclonium appears.

Rhizoclonium Characteristics:

  • This type of hair algae has the appearance of pale to light green clusters of filamentous shape.
  • It is very mucous to the touch.
  • These are thread-like and form large tangled coarse mats.
  • The slender filaments may reach up to 5 cm (2 inches), they do not branch.
  • Cells are large, long, and cylindrical. They are 2 to 4 times longer than wide, seen under magnification.
  • In nature, Rhizoclonium does not attach to a substrate and can even float near the surface, held up by the oxygen they produce. In the aquariums, it is vice versa, these algae often start to grow from the surface of leaves, decorations, and from the substrate.
  • These hair algae prefer to grow in shallow and hard water in similar places as Cladophora, to which it is related.
  • According to the study, Rhizoclonium can grow even in diluted seawater.

Common Causes:

  • New tank setups and unfinished nitrogen cycle.
  • Low maintenance.
  • Very low CO2 level.
  • Very low water flow.

How to Remove Rhizoclonium Hair Algae:

This is by far the easiest of 4 types of hair algae.

2. Oedogonium

Oedogonium Hair algae in aquariumsThe Oedogonium is a common hair green algal group in freshwater tanks. Their holdfast cells allow these algae to firmly attach almost to any surface including plants and the substrate.

These algae look very fluffy and often appear on weakened or dying plants. It can be found both in new and matured tanks. In some cases, it can appear after massive trimming.

Oedogonium Characteristics:

  • The main characteristic feature by which the Oedogonium hair algae can always be accurately recognized among other filaments is the “caps” present on some cells.
  • Color ranges from dark green to yellow-green.
  • These hair algae do not feel slimy to the touch and do not slip from the
  • Very fast growth rate.
  • It prefers to grow in tanks without strong flow.
  • Filaments are made up of uninucleate, cylindrical cells.
  • Although it has male and females sells, these hair algae are very versatile and can reproduce by vegetative, asexual, and sexual methods.

Common Causes:

  • Hair algae of this group are usually associated with a low concentration of macronutrients, too high or too low level of nitrates (NO3), and phosphates (PO4) in the tanks.
  • Unstable or very low CO2 level.

How to Remove Oedogonium Hair Algae:

  • Contrary to popular belief, Oedogonium hair algae are poorly eaten by most shrimp and fish species (except Amano shrimp). Siamese Algae Eaters, Nerite snails, Otocinclus Catfish may eat it when they are hungry and algae are not too big.
  • Remove heavily affected parts of the plants.
  • Use a toothbrush to remove it manually.
  • Adjust nitrate and phosphate levels in the tank.
  • Some aquarists use a one-time CO2 injection (20 ml per 100 liters or 25 gallons) during the night time for 3 – 5 days in a row.
  • Seachem Flourish Excel and/or Hydrogen peroxide will also help (read below).
  • Another option is to find algae treatment products that contain algaecide as their component. Algaecide is very effective against hair algae.

For example, Tetra Algae Control – link to check the price on Amazon.

Once the optimal conditions for the plants’ growth are restored/created in the tank, Oedogonium hair algae usually get weaker and disappear. In a balanced tank, it cannot compete with plants for nutrients.

3. Spirogyra

Spirogyra Hair Algae in AquariumsSpirogyra (also known as pond silk) is one of the most common freshwater green algae in all parts of the world. There are more than 200 Spirogyra species, some of them can even be found in brackish waters.

Even though it is fragile to the touch, it is one of the most difficult to remove hair algae in the aquarium hobby.

Spirogyra Characteristics:

  • In the aquarium, it looks like small bright green strands.
  • Feel slimy and slippery to the touch due to a mucilaginous coating.
  • Free-floating and able to form cottony brown mats.
  • Spirogyra has very long, unbranched filaments that can grow up to 15 cm (6 inches) or more.
  • Reproduction can be vegetative (cell division) or sexual (conjugation).
  • Multiplies very quickly. In an aquarium with good lighting, it can literally cover all plants and decorations in just a few days.
  • The filaments often grow parallel to each other, rather than twisted. If needed it can be separated into strings.
  • Spirogyra hair algae prefer quiet to slow-moving waters.
  • These filamentous algae are characterized by ribbon-shaped chloroplasts that are arranged in a spiral form inside the cells. This unique characteristic gives a glistening look in the water.

Common Causes:

  • Too much light in the tank.
  • Lots of organic waste.
  • Too much micro-nutrients in the water.
  • According to the study, the high content of nitrogen and phosphorus can trigger infestation.

How to Remove Spirogyra Hair Algae:

It is extremely difficult to deal with Spirogyra in the tanks.  The main problem is that in order to grow, it has the same needs and requirements as aquarium plants (lots of nutrients in the water, good lighting, and even carbon dioxide (CO2)).

  • Manual removal as much as possible.
  • Cut the fertilizers dosing to at least 50% or even stop it.
  • Blackout for 3 days.
  • Drastic reduction of daily photoperiod to 2 – 4 hours after the blackout.
  • Introduction algae-eaters like Amano shrimp, Florida flagfish, and hoping that Spirogyra hair algae will not grow too fast for them to keep up with it.

There is a very high chance that without algae-eaters, lowering lighting period, fertilizers in dosing, and blackouts will not work. In this case, we can use chemicals Excel + H2O2.

Seachem Excel + H2O2 vs Spirogyra Hair Algae

Although you can use Seachem Exel and Hydrogen peroxide separately. They are most efficient as a combination. You need to create a 50/50 mixture of 3% Hydrogen peroxide and Seachem Excel.

Potential problems: You have to understand the risk. Hydrogen peroxide + Seachem Excel can be too much for your beneficial bacteria, livestock, and plants (like mosses) to handle. This is very dangerous but also effective even against tough algae as Black beard algae

Day 1

  1. Reduce daily photoperiod to 4 hours.
  2. Manually remove as much algae as you can.
  3. Do massive water change (50 – 80%) to remove free-floating algae particles from the water column. Important: Besides the fact that the concentration of this treatment is not safe for the animals, especially for the shrimp, huge water changes can also cause serious molting problems for the shrimp.
  4. Increase aeration. When the algae start to die off, they will begin to decompose. This process will absorb lots of oxygen. Depending on the situation, it can even suffocate your fish or shrimp.
  5. Turn off your filter (Note: Ideally, you need to remove filter media so that beneficial bacteria will not be affected. In this case, you can keep the filter running for additional water flow).
  6. Use the mixture of Hydrogen peroxide and Seachem Flourish at 1 ml per gallon or per 4.5 liters (Gently stir the water to spread it, if you turned off the filter).
  7. Wait 1 hour.
  8. Turn your filters back on or put the filter media back.

Day 2 and day 3:

  1. Keep daily photoperiod to 4 – 5 hours.
  2. Do a water change and add your favorite bacterial supplement back to the tank.
  3. Turn off your filter (Note: Ideally, you need to remove filter media so that beneficial bacteria will not be affected. In this case, you can keep the filter running for additional water flow).
  4. Use the mixture of Hydrogen peroxide and Seachem Flourish at 1 ml per gallon or per 4.5 liters (Gently stir the water to spread it, if you turned off the filter).
  5. Wait 1 hour.
  6. Turn your filters back on or put the filter media back.

Seachem Flourish Excel and H2O2 vs Spirogyra Hair AlgaeBy this time you should notice some changes:

  • No new algae growth.
  • Some dead algae patches.
  • Algae became pale, short and start to recede.

If you are satisfied with the results you can start gradually increase photoperiod and dosing.

Hydrogen peroxide link to check the price on Amazon.
Seachem Excel  – link to check the price on Amazon.

Tetra Algae Control vs Spirogyra Hair Algae

This product specifically manufactured to combats aquarium algae, and prevent it from returning. Algae Control is highly effective against:

  • green water (algal blooms),
  • bluegreen algae,
  • diatoms or “brown algae,”
  • hair algae or blanketweed that grow on the glass and décor.

Although it is safe for established planted aquariums (more than three months old), it is not safe for invertebrates or crustaceans e.g. crabs, shrimps, or crayfish.

Tetra AlgaeControl Freshwater Aquarium vs hair algaeTreatment:

  1. Manually remove as much algae as you can.
  2. Remove activated carbon filters for 6-8 hours after dosing.
  4. Add 1ml of Tetra AlgaeControl for every 12 gallons (45L) of aquarium water. DO NOT OVERDOSE.
  5. Make sure the aquarium is well aerated.
  6. Repeat if needed every 3 days for up to three total doses.
  7. Clean out additional algae as it is killed to prevent deterioration of water quality.
  8. Do a partial water change.

Tetra Algae Control – link to check the price on Amazon.

4. Cladophora

Cladophora Hair algae in aquariumsFirst of all, there are many varieties of Cladophora that are grouped into a general category of hair algae. However, for aquarium purposes, we can divide all of them in two main categories:

  • Beneficial
  • Harmful

For example, Marimo moss ball is also a species of filamentous green algae (Cladophora aegagropila or Cladophora sauteri). They are commonly used in the aquarium for decorating the foreground and midground.

Unfortunately, all other Cladophora species are nuisance algae and should be removed immediately from the tanks.

Cladophora hair algae are also often confused with Rhizoclonium hair algae. As we already know, Rhizoclonium algae are the easiest to remove and it often disappears by itself. So, people let it grow and do not take any action. This is a mistake.

Note: Unlike Cladophora, the Rhizoclonium filaments are more tender and slimy to the touch.

Cladophora Characteristics:

  • Color ranges from bright to deep green (most often).
  • It has a swamp smell.
  • Feel coarse and springy to the touch. The filaments spring back when crushed in the hand. Unlike other types of hair algae, these algae have no mucilaginous coating.
  • Can firmly attach to any surface including the substrate or can be free-floating.
  • Creates mat-forming colonies.
  • These hair algae do not afraid of water flow and can survive in fast-flowing water.
  • Cladaphora algae grow huge! In the aquariums, their strands can reach up to 30 cm (12 inches) long. In nature, this alga can grow up to a few meters.
  • Most Cladophore species prefer cold temperatures.

Common Causes:

  • Unknown

During my research on Cladophore hair algae, I found lots of controversial information. For example, some sources say that low concentration of macronutrients, nitrates (NO3), and phosphates (PO4) may cause it in the tanks. At the same time, I know for sure that people got these algae when they had enough macronutrients, nitrates, and phosphates. The same is with CO2, water flow, lighting, etc.

Even though, it is not clear what exactly triggers Cladophore., I believe that it is an excess of nutrients. The reason behind this idea is pretty simple. Cladophora is the most ‘plant-like’ of all algae.

Like Spirogyra, it has the same needs and requirements as aquarium plants (lots of nutrients in the water, good lighting, and carbon dioxide (CO2)). The difference though is that Cladophore algae have a more complex structure, therefore, it is closer to plants as a ‘higher life-form’. Basically, we have to treat it almost like a plant. (Remember, Moss Balls are a species of Cladophora).

So, if it is so close to plants – nutrients might be the most important factor in this equation.

How to Remove Cladophora Hair Algae:

This is the hardest hair algae out of all. In some cases, it can be easier to completely tear down the tank than to fight Cladophora for weeks and even months.

It is not afraid of either shading or bright light, it feels fine both in cool and warm water. Some Cladophora species can even live in marine and freshwaters, they are capable of withstanding 5–30 ppt salinity.

Killing Cladophora selectively in a planted tank is nearly impossible. It must be a combination of different methods. Be ready that some of them will not work for you.

In any case, we should first always try to balance all parameters in the tank. Even though Cladophora is another ‘step of algae evolution’ it can still be out-competed by plants. This factor will give us an advantage while we use other methods.

  • Manual removal. In some cases, when it attaches to the substrate, you may have to remove that part of the substrate. Because Cladophora will leave spores there.
  • Spot treat with H2O2 and/or Excel for mild cases.
  • Overdosing H2O2 and/or Excel for the bad cases.
  • API algaefix.
  • Optimizing CO2 and nutrient levels.
  • Long blackout.
  • Easy Life AlgExit.
  • Algae-eaters (Amano shrimp).

Overdosing H2O2 and / or Excel

I have already described these methods, the only difference is that Cladophora is a very hardy and resilient alga. Meaning that you may have to increase the concentration of H2O2 and / or Excel to deal with it.

For example, instead of 1 ml per gallon (per 4.5 liters), use 1.5 ml or even more. Once you see that Cladophora became pale, it is a good sign for you.

You have to understand that these concentrations can be very dangerous not only for fish, shrimp, etc. but for the plants as well. There is a very high chance that some plants (especially soft ones like mosses) will not make it.

Optimizing CO2, nutrient levels

If you use CO2 injections, you need to slightly lower the CO2 level for a week or more.

Next, increase the CO2 level a bit higher than normal. Do not forget to manually remove Cladophora all the time.
By doing so in well-established tanks, plants will have a boost that can help to eliminate the algae. However, if there is no balance in the tank, Cladophora can also adapt to changes pretty well.

You can read more about it in my article “How to Remove Algae with Plants”.

Long blackout

Cladophora does not care about 2 – 3 days blackouts. In most cases, it will not work. The only option here is to increase it to 7 – 14 days. Unfortunately, it can also be a problem for the tank.

Therefore, we can use this method only when it is possible to remove the ‘infected’ plant from the tank.


API algaefix vs hair algaeThere are some positive reports that AlgaeFIX can completely eradicate Cladophora.

The problem though, it is not safe for invertebrates including shrimp, snails, crayfish, etc.

Even more, in spite of the description that it “controls many types of algae in aquariums and will not harm to your fish or plants when used as directed”. There also some complaints that AlgaeFix also killed fish, even when dosed according to the bottle.

API algaefix – link to check the price on Amazon.


Most algae-eaters refuse to eat Cladophora. Even Amano shrimp will not do that if there is something else in the tank. Therefore, we have to stop feeding Amano shrimp at all. They must be very hungry.

Note: Amano shrimp can be especially efficient in combination with blackout method.

In Conclusion

Any disease is easier to prevent than to cure. This rule is also true in the case of the uncontrolled growth of hair algae. The very appearance of algae in the tank is a clear signal for the aquarist that there is an imbalance in nutrients, lighting, and maintenance.

And last but not least, do not forget to quarantine all plants. You have to treat them before adding them in the display tank. Never put a plant with any visible algae on it. It will save you lots of headaches like hair algae or parasites (like pest snails or Dragonflies). Even though some plants may not survive dipping, in my opinion, this is the price we have to pay.

Related articles:

How to Remove Hair Algae in Aquariums pinterest

2 thoughts on “How to Remove Hair Algae in Aquariums

  1. I cannot tell you exactly what type of hair algae I had ( i might have had all of them). In general I had a lot of issue with nutrient deficiencies in my tank. After fixing one another would show up. Overall I had N, Ca, Mg, Cl, Fe , and Cu deficiencies and I suspect sever others. While dealing with this deficiency issue sometime the hard algae would melt away very quickly. Typically when the plants were growing well. When the plants were not growing well Hair algae would overwhelm the tank.

    Based on the above experience I concluded hair algae was a symptom of a nutrient deficiency. If I had a nutrient deficiency i had it. If nutrients were OK hair algae retreated. Ferthermore I observed no hair algae when I had a N, Mg, or CL deficiency. That means hair algae most frequently occurs when there is a shortage of any of the following non mobil nutrients: CA, S, Fe, Mn, B, Zn, Cu, and maybe nickel. Only 2 are macro nutrients. The rest are micros. It took about 5 years but now I don’t worry about this algae.

    Note I used several fertilizers with GH boosters Flourish comprehensive, CSM+B and NPK, Flourish trace with iron, and NPK. I had hair algae with all of them. Water was RO with A TDS of 1ppm, and an inert substrate. Most fertilizers on the market assume your tap water is supplying all or most of the Ca, Mg, Zn, and Cu. If your water is short on any one of these you will get hair algae.

    So with My RO and inert substrate setup most commercial fertilizers will not work. So to fully resolve this issue I had to make my own macro, and mix my own N, P, K fertilizer and GH booster ( 1 part magnesium sulfate , with 3 parts Calcium chloride. Micro fertilizer dose is currently 0.1ppm Fe FE DTPA, 0.05ppm Mn sulfate, 0.02ppm boric acid, 0.02ppm Zn sulfate, 0.01ppm Cu sulfate, 0.04 sodium molybdate, and 0.004 Ni sulfate. I mix that in water with a ph of 5 or less (RO with citric acid). And add 1ml of that per week into my small tank.

    1. Hi Steven F,
      Thank you for sharing your experience!
      Best regards,

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