why is aquarium water cloudy? Causes and 5 Treatment Remedies

Cloudy water in an aquarium is not only ugly, but also dangerous for all its inhabitants. There can be a lot of problems: from improper care to the development of the simplest algae. The problem should be resolved as quickly as possible so as not to endanger fish and plants. Prevention consists of following the rules, as well as controlling the microbiota of the aquarium with proper fish aquarium care.

why is aquarium water cloudy

Why Is Aquarium Water Cloudy?

The aquarium has been bought, the ground has been laid, the plants have been planted, the decor has been arranged. The only thing left is to start the water, install the filter and land the fish.

All conditions are met, the fish are settling in a new house, the snails began to polish the inner walls. But after a few days, the water changes color, turbidity appears, and in some cases an unpleasant odor. The following reasons are to blame.


Some types of aquarium substrates are capable of staining the water, creating a cloudy white hue. Therefore, before laying it, it is important to rinse it well until the water in the container becomes completely transparent.

If you don’t have time to mess around with multiple rinses, you can fill the soil with hot water by adding a few tablespoons of vinegar. Let stand for 10 minutes, then rinse 2 times with running water.

A cloudy gray and black shade of water is formed if the soil is incorrectly laid under the roots of the plants and there is no top layer. When the filtration station is turned on, a current is created that can raise the bottom sediment along with particles of nutrient mixture, which creates turbidity.


When a large amount of feed is poured out, which is several times higher than the recommended rate, some of it will surely settle to the bottom.

Naturally, this is necessary and important for bottom dwellers, but an overabundance leads to the activation of natural processes of putrefaction and decomposition.

Large amounts of carbon dioxide and ammonia are released, causing turbidity.

Even the most powerful filters will not cope with their task if you feed the inhabitants of the aquarium very often and in large portions.

Experts recommend organizing a feeding area for fish in a specific part of the aquarium. This will help concentrate feed residues in one part, which can be removed more often with a filter.

With an excess of feed and its decomposition, a cloudy yellow, gray and greenish tint of water is formed, which is accompanied by an unpleasant odor. The inhabitants become inactive, lose their appetite, and move slowly. Plants are covered with bloom. Bottom fish die during long-term turbidity of the water.


In order to save money, novice breeders deny themselves the pleasure of purchasing blue lamps, which are most suitable for the full and comfortable existence of all living things in the aquarium. The replacement is trivial: a conventional incandescent yellow light bulb.

It is also cheaper, and heats the water in the cold season (no need to spend money on heating), and creates additional lighting in the room. But it is only at first glance that there are so many advantages. 

In practice, there are solid cons, and they will appear in the near future:

  • Yellow light and excess heat causes active water bloom. Optimal conditions are created for the development of bacterial flora and protozoan algae.
  • Water evaporates faster, you need to constantly monitor its level.
  • Under the influence of such light, the processes of decay of feces and bottom debris occurs 7 times faster. The water is oversaturated with ammonia, from which all living things in the aquarium suffer.

This reason is accompanied by the following signs:

  • water with a green and yellow-green tint;
  • unpleasant hydrogen sulfide odor;
  • plaque in the form of green spots on the walls of the aquarium;
  • filamentous growths on decorative elements and plants.

The problem also occurs in those aquariums where the lighting is selected correctly, but the daylight regime is not observed. It is not recommended to give backlight around the clock, as algae and bacteria develop faster in the light.

Experts recommend not turning on the lights in the aquarium 1-2 times a month. This will help control the growth of protozoa and keep the process within limits.


The rules for maintaining aquariums assume a weekly replacement of part of the water.

For this, 1/3 of the total volume is drained bypassing the tube along the bottom (this is how the accumulated sludge is additionally removed).

Add clean, settled water to the desired mark, which will allow you to keep the aquarium clean for a long time.

  • When the water stagnates, a cloudy gray or greenish tint is formed, as well as an unpleasant odor. If the situation is critical, then a complete cleaning is performed using disinfectants.
  • In addition to water, it is important to monitor the condition of the bottom. If there is a brownish-brown or green plaque, an unscheduled cleaning is necessary. If there are dead inhabitants, they need to be removed as quickly as possible and part of the water replaced.


In large aquariums with a large number of fish, special filtration stations are used, which purify the water more efficiently. With an incorrectly selected filter, the water will stagnate, and the bottom sediment will rot at a high rate and poison the life of the fish.

Aquarists advise cleaning the filter element once a week. This will help to increase the quality of filtration, as well as protect against unwanted damage.


To create coziness for the inhabitants of the aquarium should only be from those elements that are intended for these purposes.

A beautiful skull or chest jewelry box submerged in water can absorb water and decompose, staining the water. For this purpose, it is not recommended to buy decorative elements outside of pet stores.

Cheap plastic aquarium greens do more harm than good. Low-quality material, with prolonged contact with water, emits harmful substances that not only stain, but also make the water unsafe.

5 Treatment Remedies for Aquarium Cloudy Water

The first and foremost task for the aquarist is to find the cause and correct it. The water can be changed indefinitely, but if the real problem is not eliminated, there can be no talk of any transparency, beauty and safety.

treatment remedies for aquarium cloudy water


If the situation is critical, and the water is so cloudy that it is impossible to determine the number of fish, a general cleaning is needed using special disinfectants. We carry it out step by step:

  • We plant fish and other representatives of the fauna in a separate container.
  • We carefully remove plants and decorative elements.
  • We drain the water, collect the soil in layers with a spatula (if several types are used), transfer it to a separate container.
  • We clean the aquarium: with the hard side of the sponge we go along the walls and bottom. We use soda and coarse salt as a detergent. We carry out the procedure several times, rinsing the glass container well.
  • We process the soil: we wash it 5-7 times under running water to wash out the sediment. Fill with disinfectant or boiling water. We brush large stones separately. Fill the cleaned soil with water, let it stand for 1-2 hours.
  • We treat the aquarium with a special disinfectant, rinse it with water, and install it in its usual place.
  • We lay the soil, add a little water, plant the plants, arrange the decor elements, add water to the desired mark.
  • Be sure to let it stand for 5-6 hours, after which we plant the fish.

Decor elements should be cleaned with a stiff brush to remove all plaque. Such general cleaning should be carried out once every 2-3 months or unscheduled when the situation with turbid water is critical.


If the water turns very green and the balance of microflora is disturbed, it is necessary to add natural purifiers to the water. They are of two types:

  • Liquid solution – contains beneficial bacteria that fight protozoan algae and inhibit their growth.
  • Insoluble tablets – the active ingredient is released slowly, but the effectiveness lasts for many months.

These products are safe for flora and fauna, help to filter the water naturally, and also provide additional aeration to the aquarium.


Before replacing part of the water in the aquarium (once a week), you need to “siphon” the bottom. For this, in close proximity to the ground, they are passed through with a hose, from which water naturally flows into a prepared container. This way you can remove up to 90% of the remnants of rotting food and feces, which will reduce the frequency of general cleaning.

The filter needs cleaning 1-2 times a week. It is disconnected from the network, the filter element is removed, and it is washed well under running water.

Experienced aquarists always disinfect the filter, which prevents the development of pathogenic flora in it. For these purposes, a chlorine solution, hydrogen peroxide or vinegar is used. Before placing it in the aquarium, rinse it well several times to remove any cleaning agent residue.


It is better to feed the fish 2 times a day, but in small portions, than once a week, but with a whole pack. If the food is not eaten within the first 3-5 minutes, it will surely settle to the bottom and begin to rot.

  • To this end, it is necessary to settle bottom dwellers in the aquarium, which will help fight this problem. Catfish, snails and shrimps have proven themselves well.
  • Add plants to your aquarium that can inhibit the activity of protozoan algae. They not only diversify the decor, but also help keep the water clean and transparent for a long time.

Control the amount of cladophores in the aquarium. This decorative elementary alga can provoke water turbidity if not cleaned in time. It is not necessary to allow the whole bottom to be covered with a green bloom, since there is only one step between “beautiful” and “dull”.


The aquarium is a daily control. Maintaining biobalance is easy enough if you follow these guidelines:

  • Controlling the number of individuals – overpopulation should not be allowed, since the fish will not have enough nutrients in the water, and an excess of feces always leads to flooding.
  • Decaying plants for scrap if there is a decay process, it is better to remove such a plant than to fight the pathogenic flora later.
  • Remove the aquarium from direct sunlight – they provoke rapid water bloom due to the lightning-fast development of the simplest algae.
  • Do not ignore snails and bottom fish that aid in filtration.
  • Use biological microflora activators that are completely safe for fish and plants.
  • Thoroughly clean all surfaces during the general cleaning of the aquarium.
  • Choose the right soil and decorative elements that, with prolonged contact with water, will not stain it.
  • Use only settled water that does not contain chlorine.

Large aquariums (over 65 liters) are extremely difficult to maintain, changing the water once a month. For this purpose, experts recommend using special means that can prevent the development of turbidity in the water. The best ones are as follows.

Tetra Aqua Bactozymimproves the qualitative composition of water
promotes the growth of beneficial flora
makes turbid water transparent in a few hours
a complete breakdown of feed residues and feces
neutralization of ammonia compounds
rather a high price and high consumption
Aqua Brands Pure Watercleans water, but does not change its mineral composition
low consumption
fast activation
complete safety
the formation of flakes, which should be removed additionally
Aquarium Pharmaceuticals Stress Coat Accu-Clearsettles suspended particles
quickly filters even the dirtiest water
does not change the chemical composition of the water
low consumption
difficult to find in stores, you need to order on special sites


In conclusion, it should be noted that cloudy water in an aquarium is a reason to reconsider the features of care, as well as to think about the need to use special natural filtrates. They will help make the task easier and reduce the frequency of complete cleaning of the aquarium. If the problem repeats itself many times, then it is necessary to contact specialists who, by the type of turbidity, determine the true cause and help solve it.

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