How to Solve the Cloudy Fish Tank Problem

The eclectic art of fish keeping dates back to the Babylonians and Egyptians who considered the aquatic life sacred.  Even the great Roman empire was fond of keeping fish in tanks.  Fishkeeping is a fantastic hobby with vermiculate patterns, eccentric to-do lists, rewarding aesthetics, and lovely bready eyed companions.  However, as a beginner fish keeper, there is a lot to do and a lot more on the line.  The entire endeavor comes to an understanding of the basics and knowing that mistakes are a part of the hobby.  And one of the significant predicaments that often leaves fish keepers reeling in frustration is facing the cloudy fish tank issue.  If you don’t know the evils that cause the condition, anything you do might prove to be a waste of time and effort.  However, things get easy with a bit of guidance, so here we are, sharing our experiences and ideas to help you sustain your hobby and your aquarium.

Cloudy before clear might perhaps be a normal phenomenon.  But often, a permanently cloudy fish tank can be a fish keeper’s most feared nightmare.  It destroys your aquarium’s aesthetics, hampers the performance of your equipment, and in worst cases, when left untreated, might become a fatal factor for your tank’s inhabitants.  In this article, we will list down all the main factors that cause cloudy fish tank, a detailed discussion on how to get rid of cloudy fish tank water, and more tips on fish tank maintenance.

What does it mean when your fish tank is cloudy?

If you haven’t dealt with a cloudy fish tank, there are chances you might be thinking why we are even talking about cloudy water in fish tank?  Well, for starters, aquarium cloudiness is extremely frustrating for fish keepers; not only is it hard to treat, but when your fish tank looks cloudy, it is not the best in terms of aesthetics.  Moreover, since aquarium cloudiness is caused by an imbalance of the aquarium ecosystem, these are more significant health risks for your beloved fish.  Aquarium cloudiness simply means the stage when your clear tank water becomes a far-fetched dream because it is always foggy and murky to the point where it is hard to see the internal flora and fauna of the tank up close.

Sometimes even after conducting multiple water changes, cleaning the water media, there is no change in the predicament.  The culprits are many, but the phase always starts with new tank syndrome cloudy water.

Causes Behind Aquarium Cloudiness

Unfortunately, there cannot be a singular solution to your dilemma -how to get crystal clear aquarium water, as there many causes to what makes aquarium water cloudy.  Before rehabilitating your aquarium to a crystal-clear fish tank, you need to understand the aquarium cloudiness can be visible in several colors.  In order to diagnose the root cause behind what causes cloudy aquarium water, we must know how it manifests itself in the tank.  In this section, we will be discussing all the hues of a cloudy fish tank along with a detailed cure for these fish tank problems.

The Prime Conjecture – Improper Conditioning and Washing of Aquarium Substrate

Cloudy Fish Tank Color – Gray or White

When you see your aquarium water cloudy white, your aquarium substrate becomes the main suspect.  Almost all types of fish tank substrates, including aquarium gravel and sand, contain a fine residue within the package.  Even if the packaging states that the substrate is safe for use immediately after purchase or it is pre-washed, it will help your cause greatly if the substrate is rinsed well before you add it to the aquarium.  When the substrate is shifted around and moved during the shipment, the particle rub against each other, causing them to break down into fine particles.  With proper conditioning, you can avoid cloudy water in new aquarium. Another big mistake that results in a new water filter cloudy water is when you run the filter immediately after adding the aquarium sand or gravel.  This aquarium cloudiness is termed “sand cloud” in the fish keeping community when there is cloudy water in fish tank after cleaning.

Troubleshooting Cloudy Fish Tank from Aquarium substrate

Most of the time, aquarium cloudiness can be easily solved with a little bit of patience.  If you see white cloudy water, it is best to wait it out for a few hours.  If you are using a finer aquarium substrate, the cloudy fish tank problem might last for a few more days.  Conducting partial water changes can help as it eliminates a bit of dust in the water.

You can also try using a super fine clear aquarium filter[mechanical], which traps the excess particles in the white cloudy water.  The gist of this problem is that time is your best ally.  If you have not yet added the aquarium substrate into the tank, rinsing the product is the way to prevent the predicament.

Here is a short video guide on how to get rid of cloudy water in an aquarium

The Second Conjecture – Bacterial Bloom

Cloudy Fish Tank Color- Thick White or Gray Foggy

Bacterial bloom is a phenomenon where there is a sudden increment in the bacterial colonies present in your fish tank.  The bacteria proliferate with an impressive velocity that you might be able to see some collective strands after the condition worsens.  The dangerously higher concentration of bacteria leads to milky aquarium water in terms of appearance.  The severe the bacterial bloom gets, the harder it becomes to see the fish in the fish tank.

Cloudy water in new aquarium is more common than cloudy aquarium water in established tank.  New tank syndrome or the disruption of the nitrogen cycle are the two leading and interrelated causes when your new fish tank water is cloudy or hazy.  To tackle the predicament constructively, it is crucial to understand a few more concepts. 

Nitrogen cycle In an Aquarium- The Centre Of Aquatic Life

The nitrogen cycle in your aquarium is the cycling of several harmful and toxic compounds by the bacteria.  The phenomenon can be best explained in four steps:

  • The first stride is the decay of waste products produced by your aquarium fish and aquatic plants in addition to the decaying organisms and the leftover fish food.  As these substances continue to decay, the process results in the production of ammonia.  Even at low levels, ammonia is toxic enough to burn the gills of your fish or cut their oxygen supply.
  • The good bacteria present in the substance of the fish tank consumes ammonia, producing a by-product called nitrites.  Nitrite is another toxic compound; however, its toxicity is nowhere a match to ammonia.  Your fish can stand almost twice the amount of nitrites in the milky water when compared to ammonia.
  • Another helping bacteria called the Nitrobacter then consumes the nitrite converting it into a compound known as nitrate.  Nitrates are considerably less toxic compared to ammonia and nitrite.
  • The final product nitrate requires an anaerobic environment to be converted into the least harmful nitrogen gases.  The water chemistry parameters needed for this conversion are typically inherently present in an aquarium.

The period of nitrogen cycling takes anywhere between 2 to 6 weeks; however, the actual time frame largely depends on the condition of your aquarium.

An Imbalance in The Nitrogen Cycle

The reason why new fish tank water is cloudy more often than not is closely related to several factors that tip of the otherwise normally functioning nitrogen cycle.  As your fish, aquatic plants, and all the other components of the domestic ecosystem begin to thrive, more and more ammonia is produced.  If there is a deficiency of the Nitrosomonas bacterial colonies, the ammonia levels spike quickly, complementing the proliferation of the ammonia loving bacteria in the tank.  This is when you begin to see the wispy smoke-like milky aquarium water in the tank.

An increase in the level of nitrite in the aquarium can cause a similar cloudy fish tank.  As the number of Nitrosomonas colonies increase, the nitrite also increases.  As a result, the nitrite loving bacteria begin thriving and growing in vast numbers.  As most of the bacteria in a fish tank are aerobic, the ecosystem mostly depends on the oxygen concentration.  The heavy dependence on the oxygen levels is the factor that makes the nitrogen cycle so crucial to be maintained well.  Bacterial bloom leaves your fish gasping for little oxygen present in the cloudy fish tank water. Overfeeding your fish causes the uneaten food to sink to the bottom.  As the fish food decays, it causes an abrupt spike in the level of toxic compounds.

If you are taking care of your fish feeding cycles and the amount, and still you face a cloudy fish tank, overcrowding of the unit might be another significant cause.  Overcrowding simply means stocking your tank with way too many fish than the recommended amount.  Overcleaning your fish tank filter can destroy the established colonies of the good bacteria.  Maintaining a clear aquarium filter is a good fish keeping habit; however, it should be done in moderation.  The fish keeping community has its share of myths floating around.  The more significant one professes that the increased ammonia levels cause bacterial bloom as you might often put milky water and ammonia levels together.  However, the spike in ammonia levels doesn’t cause bacterial bloom; instead, bacterial bloom causes the rise in ammonia concentration within the tank. 

Here is a short video guide about bacterial bloom in Aquarium

Troubleshooting the cloudy fish tank due to bacterial bloom

It is essential to maintain a balanced nitrogen cycle if your goal is to prevent aquarium cloudiness due to bacterial blossoms.  The best way to do that is to ensure a healthy number of good bacteria are present in your tank to breakdown the toxic substance produced by fish waste and decaying matter.  Here are a few more management tips for cloudy water in new aquarium as well as cloudy water in established aquarium.

·         Proper Cycling of the New Fish Tank

When you are yet to transfer your fish to the aquarium, it is best to complete the entire cycling time.  Even if you see milky water chemistry, with a few days of running, the heterotrophic bacteria eat away all the organic matter, leaving behind a crystal-clear aquarium.

·         Fish Tank Maintenance in An Established Tank

If you are trying to troubleshoot cloudy aquarium water in an established tank, the best way is to ensure proper aeration in the tank.  You can supplement the oxygen concentration using airstones.  Using pH testers to monitor the level of ammonia and other gases in the water is the best method of preventing the imminent problem.

Make sure that you feed your fish according to necessity; overfeeding is a sly culprit that topples your aquarium’s nitrogen cycle pretty quickly.  Performing partial water changes is another proven remedy to alleviate bacterial bloom and aquarium cloudiness.

Related- The Advantages Of Adding an Aquarium Airstone

PRO TIP – if you are wondering – why is my filtered water cloudy? Overcleaning the filtration unit can explain the problem.  You don’t want to clean your aquarium filter to the point of sterilization.  The good bacteria residing within the filter system play a central role in keeping the nitrogen cycle stable.  Mechanical filters tend to accumulate a lot of sludge over time; hence rinsing the unit in a bucket containing chlorinated water will help. 

The Third Conjecture – Algal Bloom

Cloudy Fish Tank Color- Green Foggy

The green aquarium looks precisely what a concoction of mountain dew and milk would look like.  Yes, eww!  A cloudy fish tank that appears green can be primarily attributed to the excessive growth of unicellular algae.  A spike in algal growth generally appears either because your aquarium is exposed to too much natural light or there are elevated phosphate levels in the aquarium.  Both of these situations work hand in hand to cause a milky fish tank that appears green.  If you are a beginner fish keeper and wondering – how to keep goldfish tank water, clear?  You need to pay extra attention to the algae growth in the aquarium.

Troubleshooting Cloudy Fish Tank Due to Algal Bloom

During an algae infestation, you cannot remedy the predicament by simply conducting water changes.  The sentiment is essentially true with tap water as the source has a higher concentration of phosphates.  There are other strategies that are easy and accessible and require minimal change.  You can begin by reducing the amount of light the fish tank is exposed to.  If your aquarium is placed at a location where there is more room for incoming sunlight, it will help if you moved the unit to a different location.  However, if the ensemble does not experience much natural light, you can try cutting back on the fluorescent light you are using to illuminate the tank.  Light is a strong supporter of algal growth. If the situation seems beyond redemption, just shut off the lighting system for a few days, the green milky water will subside eventually. 

The second culprit for green milky water in fish tank is a higher concentration of phosphates.  In order to control the level of phosphates, you need to be extra careful not to overfeed your fish. Extract any dead fish from the tank, conduct punctual water changes, and avoid pH altering aquarium substrates.

Combat Excessive Algal growth with algae eater fish- Read Here

The Fourth Conjecture – Unsuitable and Unconditioned Driftwood Leaching

Cloudy Fish Tank Color- Brown or Yellow

If you are wondering- why is my new fish tank water cloudy after aquascaping with driftwood, the tannins are the cause.  Driftwood is an amazing integration for revamping the aesthetics of your aquarium.  However, using the decoration without proper consideration or conditioning can cause the entire nitrogen cycle to topple off, leading to a new fish tank cloudy water.  On the other hand, natural or organic driftwood is a boon for your fish as they love the extra fish hiding places and often nibble on the wood.  Good quality driftwood also helps in toning down the pH of the water, which is quite helpful if you are worried about cloudy saltwater tank.

After installing the newly bought driftwood, you notice brown or yellowish milky aquarium water; the leaching tannins are essentially at play here.  When prolonged, the color becomes more profound, turning to an almost blackish hue.  Tannins might make the new tank cloudy, but they are relatively harmless for your tank’s inhabitants.  In fact, some fish keepers intentionally add unconditioned driftwood to the tank, leaving the water to darken over time. In the fish keeping community, such tanks are called blackwater aquariums, which are indeed quite appealing.  If you don’t have a taste for such darker aesthetics or you simply prefer clear aquarium water, here are few ways to avoid and manage aquarium cloudiness due to tannins leaching from driftwood.

Troubleshooting cloudy fish tank due to driftwood tannin leaching

Some unique natural driftwoods do not leach or release tannins into the aquarium water. Manzanita driftwood is one such product that keeps your fish tank in its pristine clear aquarium water state.  On the other hand, products including the Malaysian driftwood will leach and color your aquarium in the darkest brown or black shade at the epitome of aquarium cloudiness, which is not so bad if you are hoping to try your hand at keeping a blackwater aquarium.  However, it is best to pre-soak and wash the driftwood thoroughly before adding it to the aquarium if you are not. 

If you have already placed the driftwood in the aquarium, unaware of the chaos it will cause, and the situation is already turning into the milky aquarium water, the predicament can still be remedied.  You simply extract the driftwood pieces from the tank and leave them to soak in a different tub overnight.  To clear the cloudy water in new tank, you can use a carbon filter that will absorb the tannins leaving a crystal-clear aquarium once again.

Learn more about aquascaping with driftwood- Read Here

Cloudy Fish Tank- FAQs

Why is my betta fish tank cloudy? The Betta fish, or the Siamese fighting fish, is one of the more infamous fish breeds for aquarists.  One of the more common and troublesome fish keeping problems is a rapidly occurring and disappearing cloudy water in betta tank with different levels of visibility.  If you are using aquarium sand or gravel without rinsing, bacterial blooms caused by overfeeding or crowding, tannins from driftwood, and algal bloom can cause aquarium cloudiness in your betta fish tank. 

Why is my fish tank cloudy with no fish? If you are experiencing problems with cloudy water in new fish tank, when you are yet to add the fish to the unit, there is a problem with the aquarium equipment or the fish tank décor items you are using.  If you have a new aquarium filter that was not rinsed before being installed in the tank, then the mechanical elements or the coagulated debris is the main culprit behind a cloudy fish tank.  The driftwood or other landscaping trinkets might be leaching the water.  Hence if you have cloudy aquarium water even when there are no fish in the tank, it is best that you rinse all the equipment once more and use aquarium safe landscaping products such as organic driftwood.

Why is my fish tank green and cloudy? Green milky aquarium water is an indicator of excessive algal bloom.  Often fish keepers confuse green aquarium cloudiness with green dust algae.  The visuals are so similar, making it harder to differentiate between the two.  The best way to determine whether the problem is stemming from green dust algae or a green cloudy fish tank is to extract a small amount of water in a container.  If the water comes out to be clean and transparent, it typically indicates that the green dust algae growing on the panels of your aquarium glass is imparting the green hue.  If that is your findings, there is no need for alarm, as green dust algae is, in fact, a fabulous aquascaping idea and harmless to your fish.  But if the extracted water comes out to be green and cloudy, there is an uncontrolled excessive proliferation of algae in the aquarium.  In this case, you can follow or guide above on methods of getting rid of the green cloudy fish tank caused due to algal bloom.

How to eliminate cloudy water and smell bad fish tanks? If your tank is well-maintained and ensures proper management, it is highly unlikely that you will ever encounter overpowering foul odor or aquarium cloudiness in the tank.  However, if the aquarium does smell putrid and you face a cloudy fish tank, the biowaste produced within the ecosystem is the issue at hand. Leftover- submerged uneaten fish food, fish excreta, dead fish or plants, and overstocking can topple the nitrogen cycle, causing further problems such as bacterial and algal blooms.  These problems further the severity of the imbalance causing aquarium cloudiness and a foul odor in the fish tank.  The best method to eliminate these culprits from the aquarium is to clean the fish tank, conduct partial water changes, using aeration devices such as airstones, and avoiding overfeeding or overstocking the fish.


Aquarium cloudiness is a common dilemma for both new and expert fish keepers.  A tiny excess or deficit of one of the elements within the ecosystem can topple the natural cycle causing cloudy water in new aquarium.  There are many factors at play here, including bacterial blossoms, tannins, algae growth, and cloudiness in basic substance.  Most cases of a cloudy fish tank can be resolved with proper fish tank management.  Maintaining a routine on aquarium care and setup is essential.  It might seem overwhelming and extensive at first, but the rewards are greater.  With a bit of extra time spent cleaning and conditioning your aquarium, you will be saving a colossal amount of stress and time fighting the culprits of a cloudy fish tank.  For it’s much better for the fish keeper to prevent than cure.  Proper management is, thus, the best habit you can develop to keep aquarium cloudiness at bay for good.

Also read – Best Aquarium Sand for Freshwater and Saltwater Aquariums

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