hairy algae

Filamentous algae


One of the most serious problems for fishkeepers is the appearance of green filamentous algae, collectively known as “hairy algae”. Some of them are relatively harmless and quickly disappear after normalization of conditions in the aquarium. Others are a real disaster, since getting rid of them is extremely difficult. There are cases when aquarists spent several months to completely overcome this scourge. In a short time, the thread can completely fill the aquarium, therefore, at advanced stages, it is dangerous for higher plants.

The struggle is hampered by the fact that the living conditions of these algae are very similar to those of higher plants, so the methods used to destroy hairy algae can also affect the plants of the underwater garden.

Most often, green hair algae affect precisely herbal aquariums, in which the regime of introducing micro and macro elements is violated. The appearance of hair algae is a signal for a revision of the applied doses.

The aquarium that “captured” the thread is a sad sight. It seems that it grows from everywhere – from the soil, on the leaves of plants and the filter. These slimy threads encircle everything they reach.

It is very easy to bring algae to the aquarium with new plants and, if the conditions for their development are comfortable, you will immediately get an algae outbreak. Therefore, before buying, it is recommended to carefully examine the leaves for the presence of hair algae.

To get rid of this scourge, it is necessary, first of all, to eliminate the causes of its occurrence, which may be an imbalance of light, fertilizers, and carbon dioxide. In especially neglected cases, algaecides come to the rescue.

About algae

Hair algae is a combined group of lower plants from the Green Algae Department (Chlorophyta). In appearance, they all resemble long thin threads that can be light green, dark green, and sometimes almost black. Algae are soft and tender in their structure, they can be easily rubbed with your fingers, and their shape can only be preserved in water – it is worth getting them out of the aquarium, as the threads immediately sag.

hair algae

Most often, the following types of filamentous algae are found in aquariums:


The fiefdom of Rhizoclonium is aquariums with impaired launch technology. If the fish were planted before the biological equilibrium was established, and, consequently, there are no colonies of beneficial bacteria in the aquarium that will process the products of the vital activity of the fish, then an increased concentration of ammonia, nitrite, and phosphate will be observed in it, which will be a great help for Rhizoclonium. The good news is that usually the seaweed itself disappears when the balance in the aquarium is finally established.


Spirogyra is one of the most difficult to remove algae, even though it is fragile to the touch. It is not easy to deal with it, it becomes necessary to use algaecides. Mechanical harvesting, a slight decrease in illumination, an increase in temperature in the aquarium, and the launch of algae-eating fish also help well.


Appears in the form of fluff on weakened plants. Usually, its occurrence is associated with a low concentration of macronutrients in the aquarium. After a week of fertilizer addition, this thread usually recedes. Algicide preparations help well.

It is most often found in freshly launched aquariums, as well as in herbal ones at startup and after massive plant haircuts. If optimal conditions are created for the growth of living plants, it usually recedes itself, unable to withstand competition with them.

Algae reproduce vegetatively – the thread simply breaks up into daughter plants. This allows it to quickly occupy new territory.

Hair algae prefers highly lit areas, in suitable conditions it can quickly spread throughout the aquarium. It is perfectly attached to any substrate: glass, soil, decorations, and plants. Strong overgrowth of filamentous algae poses a serious threat to higher plants. They envelop the plants so much that it becomes almost impossible to remove them. The plant ceases to receive the necessary nutrients, suffers from a lack of light, after which at best it stops growing, at worst it dies. The mass death of living plants can lead to the accumulation of an excessive amount of organics, nitrates and phosphates in the aquarium, which will only exacerbate problems with biological balance.

Why appears thread in the aquarium

Studying the main reasons for the appearance of filamentous hair algae allows you to prevent their mass development and organize the most effective fight. What triggers the appearance of nitrate in the aquarium?

Too intense lighting

Lighting in the aquarium must be selected taking into account the species composition of plants, their quantity, and the stage of launch of the aquarium. It is best to gradually increase the intensity of lighting and the length of daylight hours, starting from 4-5 hours a day and reaching 8-10 hours. If there are no living plants in the aquarium, then daylight hours should not exceed 4 hours a day.

It is necessary to use specialized aquarium lamps with a color temperature of 6000-6500 K (cold white light) and a special spectrum for plant growth. Warmer “yellow” lamps will stimulate the development of algae.

hair algae

High doses of fertilizer

Fertilizers are necessary for aquarium plants for proper development and good growth. Adding them to water, one should strictly follow the manufacturer’s instructions, because a lack of substances will slow down the growth of higher plants, and excess can trigger an outbreak of algae. To control the level of nutrients, you need to regularly test the water.


When starting herbal aquariums, special nutritional substrates are always used. They are laid under the main layer of soil and for a long time (up to a year) provide plants with nutrients through the roots.

Very often, such substrates contain a large number of nitrates and phosphates, which are released into the water and provoke the development of fiber. Unfortunately, the fight against algae in the presence of such a substrate will be ineffective, it must be removed, therefore, you will have to restart the aquarium.

We recommend that you use nitrate and phosphate-free nutrient substrate – Tetra CompleteSubstrate.

Macroelement Imbalance

Macronutrients include nitrogen, potassium, and phosphorus. If they are deficient, the plants stop growing and can quickly die. It is especially important to maintain an optimal ratio of nitrogen to phosphorus, it should be 12: 1. Excess, as well as the lack of macrocells, as well as their incorrect proportion, is a direct path to the appearance of algae.

Excess ammonia

The appearance of nitrate is also possible with increasing levels of ammonia in the aquarium. This phenomenon can be observed as a result of the improper launch of the aquarium, regular overfeeding of fish, overpopulation, as well as problems with the operation of aquarium equipment. But ammonia can not only trigger an algae outbreak, but it is also extremely toxic to fish. In time to learn about the excess of ammonia allow regular water tests.

How to Get Rid of Thread

To get rid of nitrate in the aquarium, first of all, it is necessary to eliminate the causes of its appearance.

Remove algae mechanically

If you find a thread, then remove it from the aquarium with tweezers or winding it on a faceted wooden stick. All that can be removed by hand or improvised means.

Shorten daylight hours

Its duration should not exceed 8 hours a day in the presence of living plants and 4 hours – without them. Do not allow sunlight to enter the aquarium – this favors the development of algae. Be sure to use aquarium lamps with cold white light (6000-6500 K) as a source of lighting, it is better to remove warm “yellow” lamps.

Adjust balance (nitrates and phosphates)

In order to balance macrocells in an aquarium, you first need to find out their level, for which water tests for nitrates (NO3) and phosphates (PO4) are done.

If the concentration of nitrates exceeds 100 mg / l, this is a critical level; it must be reduced to 50 mg / l, for which 10% of water is replaced 3 times a week.

Next, it is necessary to ensure that the concentration of nitrates is reduced to 20 mg / l, and phosphate does not exceed 0.5 mg / l. The overestimated values ​​of these parameters are often caused by overpopulation in the aquarium or regular overfeeding, so these two factors must be excluded first.

Always ensure that the number of fish in the aquarium matches the volume. The minimum recommended volume of the aquarium for each species is individual, this information can be clarified in the reference materials. For a quick assessment, you can use the rule: for every centimeter of fish for small species there should be at least one liter of water, and for large species – at least two to three liters.

hair algae


Overfeeding is also a common cause of imbalance in the aquarium because fish that eat a lot produce more waste. It is necessary to feed the pets 2-3 times a day in small portions, which will be completely eaten in a few minutes. If there is a lot of food left, it is advisable to collect it using a net or a soil cleaner – during decomposition, it can also cause the growth of nitrates and phosphates.

To safely reduce the level of nitrates and phosphates in the aquarium, use the following preparations:

Tetra NitrateMinus – 2.5 ml per 10 liters of water weekly;
Tetra PhosphateMinus – 10 ml per 40 liters of water every other day until you reach the required parameter value.
To comply with the dosage, we recommend using a dispensing cap. It is necessary to provide aeration in the aquarium so that cloudiness does not occur.

Get shrimp

If possible, plant beneficial aquatic inhabitants, Amano shrimp, in your aquarium. Eating thread hair algae, they will become good helpers in the fight against it. These crustaceans are naturally endowed with special miniature claws that allow them to effectively “mow” the thread. To keep the aquarium clean it is recommended to plant at least 4 individuals for every 10 liters of water.

Apply Tetra AlguMin Plus and Tetra AlgoStop depot

In addition to normalizing the conditions, it is recommended to use special drugs to combat algae.

A great choice is Tetra AlguMin. The active substance in this algaecide is monolinuron, which effectively fights against various types of algae, while it does not inhibit biofiltration and does not harm snails and shrimps in recommended dosages. Tetra AlguMin starts acting instantly.

In difficult cases, after 7 days, add Tetra AlgoStop depot tablets – after placement in the aquarium, the tablets do not dissolve, but the active substance is released slowly over the course of a month, allowing you to effectively fight algae.