How to clear cloudy water in your fish tank? Solutions You Need to know

Coming across Cloudy aquarium water at least once is an inevitable part of owning an aquarium. You may wonder how to clear cloudy water in your fish tank? 

And while it may appear to be a challenging chore that demands a great deal of effort and a thorough understanding of aquatic ecosystems, particularly for the novice aquarium owner; Fortunately, it does not!! 

You just require a thorough understanding of the underlying problem and, as a result, an understanding of the tactics for dealing with it in order to deal with it. Furthermore, the good news is that murky water in an aquarium isn’t always a total catastrophe.

In truth, there are a few easy techniques to diagnose and treat murky water. Here is everything you need to know. 

how to clear cloudy water in your fish tank?

how to clear cloudy water in your fish tank

Taking steps to prevent and avoid cloudy water before it occurs is considerably preferable to attempting to remove it once it has transpired.

As a result, the first step in cleaning your foggy fish tank is to understand the issue fully. Having said that, while we will talk about the causative agents later, let us check out the cure first:

  • Assembling the best Crew in Charge of Cleaning. One of the most natural ways to deal with murky fish tank water is to have a dependable cleaning crew. Siamese Algae Eaters, Otto Cats, and Nerite Snails are all members of popular freshwater aquarium cleaning crews. These fish and invertebrates all work together to devour trash and excess algae, resulting in a cleaner aquarium overall. A good cleaning team can help eat leftover fish food, which can cause bacterial and algal blooms if left to build up in the aquarium. 
  • The Aquarium should be seeded. Seeding the aquarium will prevent bacterial bloom and murky water in case of a new setup. Seeding is the process of moving substrate, plants, and decorations from an existing tank to a new one. Beneficial nitrifying bacteria is included with those products, and it’s critical for getting the tank cycling process started. In addition to reducing the length of time it takes for the water to cycle by half, seeding can lessen the risk of the water becoming cloudy.
  • Check the water in your tank. As soon as the water in your aquarium starts to cloud, have it tested for ammonia and nitrite. In several cases, the levels will be zero, indicating that there is no reason to be concerned. We realize how unsettling it might be to see cloudy water in a new aquarium. But the best advice is to wait things out and be patient. Don’t add any more fish; only feed once every other day, have your water analyzed, and forget about the filter for now.
  • Keep the tank clean by removing any dirt and debris and vacuuming the substrate thoroughly once a week.
  • Make use of a flocculant. Flocculates work by inducing the floating trash particles to clump together, making it easier for your mechanical filter to sieve out of the water. In your local fish store, look for “water clarifiers,” which is the common trade term for flocculates.
  • Don’t overfeed your fish. Adding too much fish food to your aquarium can have a number of detrimental consequences for the aquatic system as a whole. Overfeeding is a new tank that isn’t fully established with beneficial microorganisms that might cause ammonia surges. Even though typical test kits can’t identify it, ammonia itself can be a significant component in bacterial blooms. Less food means less waste, which means fewer hazy water issues.
  • To deal with yellow/brown water due to tannins, soak any wood decoratives in clean water for a given number of days before putting them in your tank to allow the tannins to seep out. However, in case you buy your decorations from a reputable fish store, the wood should be prepared to avoid this issue. Regular partial water changes, as well as a carbon filter, can help to remove some of the water discolorations. Fortunately, driftwood stops absorbing tannins after a short time; thus, the problem will eventually go away.
  •  Activated carbon media or activated carbon pads can be added to the filter to assist in cleaning the water and absorbing nutrients that feed the bacteria.
  • Overstocking should be avoided. Overstocking your fish tank is a recipe for disaster on several levels. Too many fish jammed into a tiny space can drive territorial species to become aggressive, and a lack of personal space can lead to stress, which can lead to health issues and disease outbreaks. Furthermore, overcrowding an aquarium with too many fish will overwhelm the filter system, causing bacterial bloom and cloudy water by overpowering the helpful bacteria that digest waste products. You can remedy the problem by moving some of your fish to a different tank, performing a partial water change, and thoroughly vacuuming the substrate.
  • In order to counteract greenish murkiness caused by algae growth (due to Excessive light), move or screen the aquarium away from direct sunlight and minimize the amount of time your tank lights are turned on. The hazy water problem will go away after the algae die off.

Why is My Aquarium Water Cloudy?

Any of the following factors could be the contributing factor to the cloudiness in your aquarium setup. 

To begin with, overfeeding your fish can cause your water to get cloudy as the uneaten food decomposes. At each meal, provide no more than your fish can consume in a minute or two.

Cloudy water can also be caused by overstocking the fish tank (brimming with too many fishes). Ammonia and nitrites are released by excess waste, just as they are by excess food.

Cloudy Aquarium Water: How to Overcome it? - The Aquarium Guide

Approximately one gallon of water per inch of (mature) tropical fish is recommended. It is recommended that you get the largest aquarium you can afford.

The large size of the fish tank is directly proportional to the amount of waste it can manage before it becomes an issue for your fish. 

Another possibility is that your aquarium is suffering from the new fish-tank syndrome. In the given case, when you set up a new aquarium or perform significant water changes, your water will naturally cloud up as part of the system’s natural biological cycle.

Fluctuations in the nitrogen cycle, as well as the release of gases in solution as a result of rising water temperatures, are to be blamed for the same. A 50 percent or greater water change will assist in resuming the cycle.

Also, keep an eye on your filter cartridge and replace it on a regular basis. However, a good rule of thumb is to clean your tank at least once a month or twice a month if you possess a higher fish population or fish that produce a lot of waste, like Goldfish or Cichlids.

What Causes Cloudy Fish Tank Water?

Cloudy water in fish tank

The causative agent of Cloudy Water In A Fish Tank can be any of the following.

Bacterial Blooms 

Bacterial blooms are common underlying causes of cloudy water. Several different varieties of bacteria and other microorganisms are usually present in your aquarium; however, issues might develop when one of them gets out of hand and proliferates uncontrollably.

Fortunately, bacterial blooms are often short-lived, lasting only a few days to a few weeks. A bacterial bloom should not hurt your fish, so there is usually no need to be concerned.

If a bloom lasts for a long time and doesn’t go away on its own, check your nitrogen water parameters (NH3/NO2-/NO3-) to make sure there isn’t something more serious going on.

Particulates / Inorganic Substances 

Certain inorganic compounds can cause aquarium water to be less clear, which is probably the least likely source of your cloudy or murky water.

High levels of phosphates (PO4), as well as dissolved minerals (extremely hard water, silicates, iron, and so on), can make a fish tank appear cloudy. Discolored, hazy tank water can also be caused by minute clay particles that stay suspended in the water. 

Gravel Residue

If the water in your aquarium becomes fogged with greyish or white cloudiness the moment you fill it, it’s most probably due to dust and debris washing off the new substrate, which is usually gravel.

In this case, empty your tank, remove the gravel, and wash the substrate under running water until the water flows clear to solve this problem.


A bacterial bloom or residual fish meal particles that have dissolved in the water might cause your fish tank to become hazy if you feed your fish too much. The answer is straightforward.

Don’t feed your fish too much! If at all feasible, feed your fish many times a day to avoid throwing a huge amount of food into the tank that might not be consumed. Only feed them as much as he can consume in a few minutes.

Keep an eye on your pet to monitor how much food they don’t eat and the quantity that settles at the bottom of the tank.

Algae Blooms 

Blooms of Algae Green water algae blooms can occur in new aquariums or tanks with a significant change in the water chemistry. Green water algal blooms are caused by a variety of factors, the majority of which can be easily avoided.

The source is most likely excessive light combined with high phosphates as a result of overfeeding. Although green water poses no threat to your aquarium’s occupants, it is quite repulsive.

Pollutants dissolved in water.

If the water is still murky after washing the pebbles, the problem is most likely caused by high amounts of silicates, heavy metals, or phosphates. If you test the pH of your aquarium water, you’ll notice that it’s high since the water is alkaline.

The problem should be solved by using a suitable water conditioner or pH buffer to treat the tap water. If you’re having trouble with your tap water, you might want to try RO (Reverse Osmosis) water, which you can get from your local fish store.

You might also invest in a machine that produces RO water, which will save you money in the long term.

Brimming population 

Overcrowding a fish tank often results in cloudy water. Your fish tank is a segment and sub within a micro-ecosystem.

Microorganisms and bacteria in that ecosystem assist in handling fish waste, rotting food, and plant detritus while your filtration system cleans and oxygenates the water. Any ecosystem, even fish tanks, can only support only a given number of life.

Overcrowding the tank with too many fish causes the filtration mechanism to fail, and the bacteria colonies that treat fish waste become overwhelmed. This culminates in bacterial growth in the water, resulting in a darkened aquarium.

As a result, it is recommended that you either keep a low fish population (a ratio that aligns with the size of your tank) or buy a larger tank for your fish. 

Does Your Tank Have White or Gray Cloudy Water?

Fish tank

Yes, that is possible. In fact, there are several shades of murky, which signifies what’s producing the fogginess. The invasion of grey or white cloudiness in water is similar to pouring a large glass of milk into your aquarium.

Although the water is still clear, there is a heavy cloud that makes everything appear hazy. White or grey water in clouded aquariums can be caused by a number of factors, including: 

Dissolved Constituents

High amounts of dissolved elements, such as heavy metals, silicates, or phosphates, are most likely to blame if your substrate is clean, but the water is still murky.

If you test the tank water using a simple aquarium water testing kit, you’ll undoubtedly find that it’s quite alkaline, with a high pH level to match. You may usually remedy the problem by adding a tap water conditioner or a pH buffer to the water.

The problem may be caused by tap water in some areas. Use Reverse Osmosis (RO) water instead of tap water to remedy this problem.

You can buy RO water at most excellent fish retailers, or you can buy a RO unit, which is more cost-effective if you possess a large tank or multiple setups.

New Substrate

Suppose the water in your aquarium becomes fogged with greyish or white cloudiness the moment you fill it. In that case, it’s very definitely due to dust and debris washing off the new substrate, which is usually gravel.

Empty your tank, remove the gravel, and wash the substrate under running water until the water flows clear to solve this problem.

Bacterial overgrowth 

If the aquarium water turns hazy a few days or weeks after it’s been set up, it’s generally due to a condition known as bacterial blossom.

Bacterial bloom occurs in a new aquarium as the biological filter matures to handle the influx of fish waste, uneaten food, and other contaminants. You may notice that the water in your fish tank turns murky throughout the break-in period.

The condition, on the other hand, normally goes away on its own within a few weeks or months. In the meanwhile, maintain the tank clean by removing any dirt and debris and vacuuming the substrate well once a week. 

Reduce the feeding frequency of your fish to every second or third day in order to avoid waste food degradation. If the water is still hazy, a flocculate can prove beneficial.

Flocculates function by causing floating trash particles to clump together, making the process of sieving them out of the water easier for your mechanical filter. Look for “water clarifiers,” which is the common trade synonym for flocculates in your local fish store. 

Large water fluctuations can also cause bacterial bloom, starting a mini-cycle in which the bacterial colonies in your filter media and on the tank’s surfaces must repopulate.

 That’s why, rather than performing a single large water change, it’s best to undertake minor partial water changes on a regularly scheduled basis to avoid upsetting the tank’s delicate eco-balance.

Furthermore, Bacterial bloom can also occur if your filter is turned off overnight. Therefore, Your filtration system should operate all of the time and should only be turned off for routine cleaning and tank maintenance.

Do You Have Yellow/Brown Aquarium Water?

 It’s uncommon for aquarium water to get cloudy Brown or yellowish; however, it can happen in certain circumstances.

Although authentic driftwood and bogwood look lovely in an aquarium and your fishes will like resting on them, wood can drop the pH of the water and cause it to turn a bit yellowish tint (resembling the hues of a cold tea).

Yellow water in aquarium

This is due to the diffusion of tannins into the water by wood. However, fishes do not particularly suffer from this.

In fact, several species that evolved in tropical forest areas where the water is teeming with fallen branches and other debris are perfectly content to live in “black water.” 

On the other hand, yellowish cloudy water can obstruct your view of your fish population and make the tank appear unclean, even if it isn’t. 

Fortunately, there is a simple solution. Before putting any wood into your tank, soak it in clean water for a few days to let the tannins drain out. However, if you buy your decoratives from a reputable fish store, the wood should be seasoned to avoid this issue.

Regular partial water changes, as well as a carbon filter, can help to remove some of the water discolorations. Fortunately, driftwood stops absorbing tannins after a short time; thus, the problem will eventually go away.

Do You Have Green Aquarium Water?

The presence of algae growth in the aquarium water is almost always the cause of the water turning green. Algae are microscopic aquatic organisms that can develop on the tank’s surfaces, the decorative plants, and the edge.

Nonetheless, some algae species grow freely in the tank water, resulting in hazy aquarium water. Furthermore, while recognizing the problem is very simple, resolving it might be difficult. To combat algal bloom, you must first determine what is causing the problem.

Green Water -- Causes and Cures

Algae flourishing in your fish tank resulting in hazy water can be caused by a variety of factors, including:


Nitrates are used as a plant fertilizer and are known to promote algal growth. As a result, lowering the levels of those compounds in your tank water can assist in limiting the growth of algae, thereby resolving the hazy aquarium water issue.

You can take immediate action by changing the water, but this will not solve the problem in the long run. To do so, you must first address the source of the problem. Nitrate levels in the tank rise in accordance with the amount of fish waste produced.

Nitrate levels should ideally be around 20ppm or below, which you can achieve by performing weekly partial water changes of up to 25 to 30%, depending on the fish species you keep and the population level in the tank.

Nitrate levels should be reasonably easy to control if your filtration system is efficient and the filters are kept clean. Check your filter system’s GPH (Gallons Per Hour) value.

The GPH should ideally be at least four times the tank’s water capacity. For instance, If you have a 30-gallon fish tank, your filter system’s GPH must be 120 or above.


Phosphates arise from two places: the water supply and the decomposition of organic materials in the tank.

First and foremost, give the tank a thorough cleaning, which should include vacuuming the substrate ( which ultimately helps in getting rid of fish waste and uneaten food) and cutting any dead leaves from the plants.

Next, test your tap water supply, as your home water supply could be the source of the problem.

The water quality requirements for all residential water supplies under the Safe Drinking Water Act (SDWA) of 1974, was established by the US Environmental Protection Agency.

Under those laws, the water is chemically treated to eliminate bacteria and other impurities, making it suitable for home use and consumption.

If the water has a high phosphate level, you’ll need to use RO water or a chemical to eliminate the phosphate before filling your aquarium.

Excessive light

Algae can develop in your aquarium water if you expose it to too much intense light, especially the sunlight.

You can prevent algae growth by relocating your aquarium out of direct sunlight or covering it with shades or drapes throughout the day when the sun is shining on it. It would be useful if you also used a timer to decrease the amount of time your aquarium lights are on.

When the algae are deprived of light, they will eventually die, and your filtration system will remove the green algae from the water, making it clean once more.

A Bacterial Bloom May Signal Danger to Your Aquarium Fish

Bacterial bloom - Aquascaping Wiki | Aquasabi

If the water in your fish tank has turned milky and you haven’t recently added a new substrate, you may be dealing with a much more serious issue, that is, a bacterial bloom.

Bacterial bloom, or bacterial blossoming as it’s often called, happens as a new biological filter system matures. 

To put it in simple words, it occurs when the population of heterotrophic bacteria (bacteria that eat organic molecules) in the water column explodes. Furthermore, Heterotrophic bacteria do not infect or directly affect the fishes.

Normally, they are always present in all aquatic settings, only lurking in the shadows. However, when there is a lot of organic material in the water for them to eat, their numbers might increase. This can be brought on by:

  • Filtration is insufficient for the size of your tank or the number of fish you have.
  • Overfeeding — germs in the aquarium feast on uneaten food. 
  • Cleaning your filter too much and too often, thereby eliminating the colonies of helpful autotrophic bacteria that dwell in it.
  • Dead fish in the tank — a dead fish decomposing in the tank can seriously contaminate the water.
  • Overcrowding — much higher populations of fish for the tank’s capacity. 

The bad news is that, while the bacteria do not directly cause illness in fish, they impose a detrimental impact on the water quality, which in turn can make your fish sick.

Furthermore, did you know that turning off your filtration system overnight might cause bacterial bloom? Your filter should ideally be running 24 hours a day, seven days a week, with the exception of when you’re cleaning or changing the filter material.

In order to avoid bacterial blooming, you can use flocculates, which are water additives, to help clarify your water.

Flocculates operate by causing microscopic floating debris particles to cluster together, allowing your filtration system’s mechanical element to remove them from the water, effectively healing the cloudiness.

Another point to keep in mind is that Large Water Changes Should Be Avoided!! 

Many aquarium owners unintentionally induce bacterial bloom by making large water changes which ultimately disrupts the delicate eco-balance within the aquarium.

Aquarium, Fish, Fish Tank, Sea Life, Ocean, Corals

This is because when you remove too much water from your tank, the beneficial bacterial colonies that exist in your tank and in the filter media begin to repopulate, it can start a mini-cycle. Stick to partial water changes of 25 to 30% weekly.

However, if you do need to change half the water in your tank for any reason, make sure to add a filter-boosting solution to the water.


While cloudy or milky water is one of the most common problems that aquarium owners face, the good news is that murky water in a fish tank isn’t always catastrophic.

In fact, diagnosing and treating murky water can be done in a number of ways. All that is required is to identify the correct reason and work toward correcting the problem.


What should I do if the water in my fish tank randomly becomes cloudy? 

Make a large water change, but don’t go overboard about the same. If your aquarium is already established and the problem is just coincidental, attempt a 50% water change and wait a few days. Give the tank some time to adjust if you don’t detect ammonia (NH3) surge (you can always check). When bacterial blooms consume all of the factors that caused them to develop in the first place, they often resolve themselves organically.

Will cloudy water hurt my fish?

Not all forms of clouding water hurt the fish population. In fact, most don’t, at least not directly. However, certain causative agents such as ammonia surge, phosphates, etc., have the potential to harm the fish populations in the aquarium. 

How can I naturally clear the water in my fish tank?

Certain reasons for cloudy aquarium water can often be resolved organically over time. A bacterial bloom, which occurs when substances such as extra waste, particular nutrients, etc., that are normally limited become available, is the most common cause of cloudy or discolored water. In this situation, the microorganisms take advantage of this, devouring the substances, and multiplying rapidly. Therefore, once the scarce resources are depleted ( by the microbes feeding on them), the bacterial colony will eventually perish. However, if the cloudiness lasts more than a week, you’ll need to take some further steps, which I’ve already discussed.

About the author

I'm Gulshan, a passionate pet enthusiast. Dive into my world where I share tips, stories, and snapshots of my animal adventures. Here, pets are more than just animals; they're heartbeats that enrich our lives. Join our journey!