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How to Get Rid of Algae in Fish Tank

Algae in fish tank is a very common phenomenon. They can reproduce and grow rapidly in the water, and consume the carbon dioxide dissolved in the water, resulting in a rapid rise in the pH value of the water environment.

A large number of dead algae will consume a lot of oxygen in the water environment of the aquarium, thus destroying the water environment of the aquarium, affecting the growth of organisms and the ornamental effect of aquatic plants.

If the algae reproduction in the tank is particularly serious, then you need to move the tank and thoroughly remove the aquatic plants in the tank to ensure the water quality environment of the fish tank.

Green algae

8 commonly found algae in fish tanks

1. Brown algae

Brown algae are one of the more advanced groups of algae. All brown algae phytoplankton are multicellular bodies. Simple ones are branched filaments composed of a single row of cells; evolved species have differentiation similar to roots, stems and leaves, and their internal structure has differentiation of epidermal, cortical and medullary tissues, and even a structure similar to sieve tubes.

The cell wall is divided into two layers, the inner layer consisting of cellulose and the outer layer consisting of fucoidan. The chromophores are 1 to many, granular or small disc-shaped, and contain chlorophylls a and c, carotenoids, and several lutein species (mainly Murray's lutein). Because the content of lutein exceeds that of other pigments, the algae are yellowish brown or dark brown.

  • Growth time

Brown algae mainly appear in the beginning of the tank building stage. Usually it appears in the first three months of the new tank and often the fish and shrimp die for no reason, so many newbies don't know what to do.

  • Location

On the wall of the tank and on the surface of sunken wood, rocks, slow growing aquatic plants and leaves, etc.

The main reason is that the nitrification system of the water body is not well established, plus the water change is not regular enough or not enough or less.

After countless times of observation, once the nitrification system is established, the algae will gradually disappear without a trace.

The best way to speed up the nitrification system is to buy high quality nitrifying bacteria and add them into the tank according to the instructions.

In addition, regular water changes (preferably water that has been aerated), adding new water to the water body will effectively dilute the nutrients in the water body. On the one hand, provide a good growing environment for aquatic plants, on the other hand, keep the water fresh and speed up the establishment and growth of nitrifying bacteria.

The establishment of nitrifying bacteria generally has a relationship with the substrate sand. In the case of not using powder or liquid nitrifying bacteria.

There are two cases:

  • Mud: with water regulating effect, can reduce the PH value, but too low PH value, is not conducive to the establishment of nitrifying bacteria, nitrifying bacteria are generally established in about 45 days basically.
  • Neutral sand: does not have the function of water conditioning, after normal and effective management, nitrifying bacteria are generally established basically in about 30 days. During this period, try not to wash the filtering system's filtering material, even if you do, only wash one-third or one-half.

2. Silk Algae

The algae are uniseriate, unbranched filaments made of connected cylindrical cells. A cell at the base of the filamentous body is colorless and is called the fixator, by which it is fixed on the stone of running water. The cell contains a nucleus, and the chloroplasts are arranged in a transversely disjoint ring along one side of the cell, exceeding half the circumference of the cell in size, with one to several pollen-forming nuclei on top.

Filamentous cells are capable of dividing, with the exception of the fixation apparatus, and have both nutritional and reproductive roles. When reproducing asexually, each cell produces 2, 4, 8, 16 or 32 mobile spores with four or two flagella. Sexual reproduction is homogamous. The gametes are pear-shaped, with two flagella, and the filaments can be produced by any cell, usually 8, 16, 32 or 64. Asexual reproduction and sexual reproduction can occur simultaneously on a single filamentous body.

Usually after the brown algae, i.e. about two months after the establishment of the tank, sometimes also after the growth of other algae, such as black hair algae. When the brown algae just disappeared, many times the filamentous algae will take root on MOSS, bottom sand and slow growing aquatic plants. I often hear people say, the original disappearance of so-and-so algae is too powerful silk algae.

In fact, there is a point to say ……In some information, if there is silk algae in the tank, it should be said that it is a congratulatory thing - the water quality in your tank has been stable, good water quality performance, fish and shrimp will not die for no reason. The next thing to do is how to control and remove it.

Frequent locations:

Needle-leaved aquatic plants such as MOSS foliage, on top of bottom sand, on the roots of slow growing aquatic plants and on sunken wood.
Generated by:

  1. Lighting is too strong, lighting time is too long and aquatic plants are too little
  2. Fertilizer added too much
  3. Too many fish and overfeeding
Treatment methods:
  1. Appropriately reduce the intensity and time of lighting
  2. Reduce the amount of fertilizer added
  3. Throw away the overgrown algae with a discarded toothbrush.
  4. Put in a lot of grass shrimp, grass shrimp is the best means to manage silk algae, but rely on a large army to fight.
  5. Control the number of fish and feed the right amount of feed

3. Cyanobacteria

Cyanobacteria are prokaryotes, and most of them have a gelatinous coat outside the cell wall, so they are also called sticky algae. In some nutrient-rich water bodies, some cyanobacteria often proliferate in summer, and form a layer of blue-green and fishy floating foam on the water surface.

The green tide causes water quality deterioration, and in serious cases, the oxygen in the water is depleted and causes the death of fish. In addition, some species of cyanobacteria produce toxins (MC), and about 50% of green tides contain large amounts of MC, which is directly toxic to fish. Cyanobacteria are unicellular plants without a nucleus, but the center of the cell contains nuclear material, usually granular or reticulate, with chromatin and pigments evenly distributed in the cytoplasm.

All cyanobacteria contain a special blue pigment, hence the name cyanobacteria. But cyanobacteria are not all blue, different cyanobacteria contain some different pigments, some contain chlorophyll, some contain cyanobacterial lutein, some contain carotene, some contain cyanobacterial cyanobacteria, and some contain cyanobacterial phycoerythrin.

The color of cyanobacteria in aquarium is green, black and brown, there is a white one (white is not sure, the shape is very similar) and so on, like snot covering the surface of the bottom sand, there is a special smell.

The location of the cyanobacteria: the bottom sand, the contact surface between the bottom sand and the tank wall.

  1. Water hardness is too high
  2. The bottom sand is too fine (this article is controversial, there is an explanation later, you can not be a reference)
  3. Use of poor quality fertilizer to cause substrate corruption
  4. Too much fish and shrimp, overfeeding.


Use the sand washer to suck it out, and appropriate to increase the number of water changes. It is best not to use tools fish and shrimp, easy to cause fish and shrimp discomfort, there will be dead fish and shrimp phenomenon.

4. Green water

In fact, many grass friends may have had this experience: the clear and transparent water, suddenly feel foggy and opaque, and gradually become foggy green, this is the emergence of green water.

  1. Light intensity and time is too strong, too long, direct sunlight.
  2. Insufficient filtration strength
  3. Water change is not diligent
Treatment methods:
  1. Reduce the light
  2. Strengthen filtration
  3. Strengthen the water change
  4. The use of ultraviolet lamps to kill the spores that cause green water, but be careful not to leak ultraviolet light caused by personal injury.

5. Green spot algae

Green spot algae (GSA, greenspotalgae) is a green spotted algae less than 0.5mm in diameter, preferring stronger lighting, usually attached to the glass surface of the aquarium with strong light or slow growing aquatic plants.

When the concentration of CO2 or phosphoric acid (PO4) in the aquarium is low, green spot algae will appear. The texture of green algae is very hard and the effectiveness of common algae eating fish to remove green algae is really limited.

Green spot algae is a problem that many grass lovers need to face often, even the experts dare not say they have not encountered green spot algae, the problem often occurs in the location: the tank wall, broad-leaved negative aquatic plant leaf surface such as big banyan, small banyan, etc..

The reasons for this are:

  1. Light intensity is too high
  2. Light reflection effect is not good

Treatment method:

  1. Use moss rat, snail and other biological treatment. At present, the only creature that can effectively scrape the green spot algae is the zebra snail (also known as colored egg snail).
  2. Improve the reflection effect of lampshade
  3. Scrub the tank wall regularly, use credit card and other tools to scrape it out.
  4. Cut off the old leaves with green spots, and adjust the layout of aquatic plants to eliminate the ones that are easy to grow green spots.

6. Steel hair algae

Steel hair algae and silk algae with the same filamentous, mistaken for silk algae, after consulting and studying the relevant information, I learned that this is steel hair algae. I began to use the method of treatment of silk algae to manage, not only no effect, but also a flood of the trend.

Frequent locations:

It is different from silk algae that often appears on the edge of water plants such as moss, but it often appears in the MOSS bush and at a point in the roots of the cow hair, and becomes a mass.

Causes: I am not very clear about it myself so far.

Treatment: less place, use toothbrush to roll out, this kind of algae shrimp is powerless, more place, remove the grass together.

7. Black hair algae

I think this is the most difficult to deal with a variety of algae, once the black hair algae flooding, will be very unsightly, should be eradicated as soon as possible!

Frequent locations: sunken wood, filter inlet and outlet, bottom sand, aquatic grass blades, etc.


  1. The PH and hardness of the water body is too high
  2. Too much residual bait into the water body
  3. Too many fish
  4. Improper composition of liquid fertilizer added to the tank, resulting in imbalance of elements
  5. Use of poor quality fertilizer
  6. No water change for a long time, resulting in nutrient accumulation
  7. Insufficient filtration capacity

Treatment: Once traces of black hair algae are found, they should be solved at the stage when they start to occur:.

1. Biological treatment: buy black line flying fox into the tank, to each 1 / 200-300mm tank as a unit, for example, your tank length is 400mm, put 1-2, to the body roll, beautiful body shape, smaller head for good character, too big black line does not like to work.

2. Improve water quality: black hair is more likely to occur in the PH and hard water, to improve the efficiency of CO2 dissolution, softening water to reduce PH and GH is a must, generally think PH in about 6.5, GH in about 8 is better.

3. To the aquarium market don't be eclectic: see what fish are like, what all to put inside the tank, always remember, the main character of grass tank is grass, fish is just embellishment.

4. Stop using poor quality fertilizer: some poor quality fertilizer is the cause of black hair outbreak due to poor nutrient ratio.

5. Improve water quality: strengthen filtration, strengthen regular water change.

6. The use of glutaraldehyde: but this method belongs to the chemical treatment method, I have not used, many people in the forum are using, usage dosage are different, are due to the tank from person to person, here do not comment. The following is the method of fish friends, you can refer to: 2% glutaraldehyde treatment, 10-15 ml / day / 100 liters of water, for a week (buy back the solution do not add the distribution of additives. (When you buy the solution, don't add the additives, but add it from the small dose upwards to prevent the fish from dying) (My 1.2m tank is about 200 liters of water, 20ml on the 1st day, 25ml on the 2nd day, the fish and grass are normal, 35ml on the 3rd day, I found that the appetite of swallowfish is reduced, the 4th to 7th day is reduced to 30ml per day, the fish and grass are normal, the black hair slowly turns red and dies. (So 10~15ml/day/100l water is safe dose) Remark: 1 glutaraldehyde may affect the growth of rootless plants, be careful with aquatic plants such as antler moss: 2 in order to avoid fish lack of oxygen, it is better to drug during the day, the following drug dose is larger, you should aerate the grass tank to increase oxygen.

7. There is another method, friends use cautiously: is according to 1:100 of 84 disinfectant, put the grass or sunken wood with black hair into it, 15 minutes or so to take out and rinse with clean water, then put it back into the tank, the black hair will become red, white and disappear in four days. This method is only applicable to ficus and other thick-leaved aquatic plants.

8. Luckhorn algae

This kind of algae is also black and looks like black hair algae, so many grass lovers mistake it for black hair algae. The biggest difference between its appearance and that of black hair algae is that black hair algae is often like a black daisy, while antler algae looks like the antlers of a buck when you look closely.

Frequent locations: edges of aquatic plant leaves, bottom sand, surface of sunken wood.

Causes of production.

  1. Too much ammonia nitrogen in the water body.
  2. Alkaline water body

Treatment methods.

  1. Reduce the amount of fish and shrimp feeding, reduce the number of fish and shrimp when necessary
  2. Improve water quality, such as softening of the water body, increase the amount of CO2 added
  3. Clean up the water plant leaves directly by hand, this is a very detailed and boring work, if necessary, remove the leaves with antler algae.
  4. Some information shows: white jade flying fox will nibble antler algae, for cleaning antler algae is quite helpful. This method I have not used, only for reference.

How to completely remove algae from fish tank?

  1. You can use a soft cloth to directly wipe.
  2. After isolating the fish and shrimp, put chemicals containing algae removal ingredients in the water.
  3. Breed "cleaners", such as fish like elf, moss cleaner, shrimp like Daiwa marsh shrimp, fire shrimp, or snails like abalone snail and army cap snail.

In aquaculture, aquatic plants and algae are always the support points at both ends of the spring. When the aquatic grass is in good condition, the algae will be naturally curbed; and when the algae is developed, the aquatic grass will not be in the best condition.

Therefore, to curb algae proliferation, healthy aquatic plants are the most favorable weapon. All the causes of algae as stated before are actually caused by one or several aspects of the main factors such as water quality, light, fertilizer, CO2, fish and shrimp quantity and feeding. Therefore, raising healthy aquatic plants is the best killer of all algae.

It is not necessarily a bad thing, it is a natural world where fish live together with algae. We should keep a normal mind while removing algae, and calmly find the cause of algae explosion, after all, water quality is the direct cause of algae explosion.

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