Skip to Content

White Particles In Aquariums: All Causes & Solutions

Disclosure: When you purchase something through my affiliate links, I earn a small commission. As an Amazon Associate, I earn from qualifying purchases.

Finding your fish tank covered in white particles can be quite disheartening. At least that’s how I felt a few months ago.

Although I had my suspicions about what these particles could be, I did extensive research on the subject and found some useful and interesting information.

Let’s dive right into it.

What Are The White Particles In My Aquarium?

If your fish tank is covered with white particles, these are usually the causes:

  • Bacteria bloom (most likely)
  • Debris
  • Air bubbles

Less likely but also possible causes:

  • Ich disease
  • Worms

Below is a brief explanation of each followed by instructions on how to identify and get rid of it:

1. Bacteria Bloom (Most Likely)

Bacteria usually thrive in aquariums that are being cycled or have high ammonia levels.

Aquariums house numerous species of bacteria. But if the filter is your primary interest, you’re probably looking for nitrifying bacteria. 

  • What Is A Bacteria Bloom?

You can’t see bacteria because these single-celled organisms are too tiny for the naked eye to perceive.

They may mimic dust-like particles in the water under the right circumstances. But you won’t see them unless they band together in significant quantities. 

Once that happens, the water will become milky and cloudy. Occasionally, aquarists will confuse bacteria with an infusoria bloom.

The term infusoria encompasses tiny animal and plant organisms. They look like tiny worms hovering in the tank.

But despite what some newcomers assume, they are not parasites. Bacteria and infusoria blooms are not that far removed from one another.

The organisms in infusoria can encourage bacterial growth by breaking down the waste bacteria utilize.

Therefore, a heavy infusoria population can pave the way for bacteria to thrive, increasing the milky texture in the tank.

  • Why Do Bacteria Suddenly Bloom?

Bacterial blooms have a fascinating relationship with filters. Bacteria thrive when they consume the nutrients in the waste that fish generate.

They break the waste down to produce ammonia. The result is a cloudy or milky texture.

Usually, you can count on the bacteria in the filter (Nitrosomonas and Nitrobacter) to convert the ammonia into nitrites and nitrates.

These nitrifying bacteria manifest during the nitrogen cycle, which typically takes between 6 to 7 weeks.

The water becomes cloudy during the nitrogen cycle because the organisms that make ammonia are running rampant.

That milky texture slowly dissipates over the days and weeks because nitrifying bacteria have started processing the ammonia

The cloudy texture in an aquarium can increase for various reasons, including:

  • You eliminated the bacteria colonies in the filter by removing the media or cleaning it too thoroughly.
  • You have neglected your maintenance routine. As a result, waste has accumulated. 
  • You did not cycle the tank to completion. 
  • The tank is crowded.
  • The aquarium is too small.
  • Where Are The Bacteria Usually Found?

Nitrifying bacteria concentrate in the filter media and substrate. 

The bacteria that produce the white particulates and misty texture don’t frequent a particular location. They tend to proliferate throughout the tank. 

  • Can I Identify The Bacteria?

You can’t see the individual particles that signify the presence of bacteria. These organisms only stand out when you have a healthy population in your tank. 

In such cases, the water becomes milky or cloudy. It looks like the tank has a white translucent mist. 

Know that bacteria may appear in other forms. Some aquarists may notice a slimy white texture, which is actually a biofilm.

  • How Do I Overcome A Bacteria Bloom?
  1. Cycle the tank to completion. Here is an article where I explained how to do that properly.
  2. Use water conditioners to neutralize ammonia and nitrites. Ideally, ammonia and nitrite should be at 0 ppm. Nitrates should be below 20 ppm.
  3. Perform routine water changes. I personally change 15 to 20 percent each week.
  4. Remove fish waste, leftovers, and dead organisms. This can be done efficiently with a gravel cleaner, such as the Laifoo Siphon Vacuum Cleaner (link to Amazon).
  5. Don’t replace the filter media. You can substitute half of it but not all of it. Also, don’t clean it too thoroughly.
  6. If your filter is new, consider adding filter media from an established tank.
  7. Use a UVC purification unit (more about it below). 

A study from the Bangladesh Fisheries Research Institute (Department of Fisheries Technology) noticed a sensitivity to UV light among fish pathogenic bacteria.[1] 

Theoretically, you can install bulbs that sterilize the aquarium by killing bacteria and parasites.[2] For the sake of full disclosure, I have never used this method myself.

2. Debris From Your Substrate

Messing with the aquarium substrate can throw up a lot of fish waste and uneaten food.

Substrate debris should be the first culprit you blame if the white particles appear after you clean the aquarium. 

  • What Is This Debris?

Every form of debris that is too heavy to float in the water will sink to the substrate. 

That debris becomes a problem when you clean the tank because it emerges from the substrate and hovers momentarily in the water. 

It is comparable to the dust particles that hover in the air when you sweep a dirty floor. Those particles will settle back down after a while. 

The debris in the tank is the same. It should only concern you if it fails to clear after a few hours. 

Don’t confuse these particles for the white buildup you see on the hard surfaces in the aquarium. 

These calcium deposits won’t rise simply because you cleaned the tank. It takes cleaning solutions consisting of vinegar and lemon juice to remove them.[3]

  • What Causes This Waste To Appear?
  1. You vacuumed the substrate. 
  2. You performed a water change.
  3. Fish are rustling up the debris as they burrow through the substrate. 
  • Where Is The Debris Usually Found?

Substrate debris will hover harmlessly in the water. It won’t frequent a specific section of the water. 

Dense debris will make the water cloudy. This may encourage aquarists to blame ammonia and bacterial blooms. 

But unlike a bacterial bloom, cloudiness caused by substrate debris will clear without your direct intervention. 

  • How Do I Know If Particles Are Debris?

Substrate debris only appears when something disturbs the substrate. That includes substrate vacuums, water changes, and burrowing fish. It also fades over time. 

Take note of the actions and events that occur before the white particles appear. 

  • How Do I Get Rid Of The Debris?

Your first option is to do nothing. The white particles will disappear after a few hours once the debris settles back down.

These white particles are not a concern unless they persist or cause ammonia and nitrite to spike too frequently.

If so, the most effective solution would be to siphon the substrate. Avoid rinsing it under tap water as it will remove beneficial bacteria.

More advanced solutions include things like a turbidity sensor. ‘Turbidity’ refers to the water’s clarity. A turbidity sensor throws a light beam at the water. 

The light beam will scatter when it encounters particles. This allows the sensor to measure the water’s turbidity.[4]

If the turbidity is concerning, you can experiment with zeolite-based water conditioners.

A study in Water Science and Technology (Lijun Shi, Jiahui Shi, Lihong Peng, Zixuan Yang, Xiwu Lu, Raana Fahim) highlighted the efficacy of natural zeolites as wastewater treatment tools.[5]

You can apply this technology to your aquarium. You can also look for filter media with fine pores (such as fine filter fleece).

3. Air Bubbles

Air stones are one of the most effective ways to oxygenate your fish tank.

Every aquarium has air bubbles. But some people confuse them for white particles, especially when their quantity exceeds the usual volume.

  • What Are Air Bubbles?

Bubbles appear because of the pockets of air in the water. People don’t notice the bubbles until they cover the surface and obscure their view of the fish. 

The bubbles will either hover in the water, rise to the top, or cling to the solid surfaces in the aquarium.

  • What Causes Air Bubbles To Appear?
  1. Filters
  2. Air pumps and air stones
  3. Fish that create bubble nests 
  4. Plants (Pearling)
  5. Agitation
  6. Soaps, detergents, and cleansers
  7. Excess protein
  • How Do I Know If The Particles Are Actually Bubbles?
  1. Bubbles caused by air stones and pumps will emerge directly from these devices.
  2. If a fish made the bubble nests, you will see this happen if you observe the tank. Fish that make bubble nests include gouramis and bettas. The bubble nests will group at the surface without popping because the fish coated them with saliva. 
  3. If an aquarium plant made the bubbles, they will usually sit on the leaves.
  4. If you have too much protein, the bubbles won’t pop because they are coated by the protein.
  • Can I Get Rid Of The Bubbles?

It is worth saying that air bubbles are a good sign as they indicate your tank has sufficient agitation and oxygen.

However, if they bother you, there are ways to reduce them:

  1. Clean the tank to reduce the bubbles made by excess protein. 
  2. If you have chemicals and detergents in the water, remove the fish and rinse the tank thoroughly. 
  3. Make sure the filter’s outlet is on the surface or just below. This will reduce the number of bubbles it makes.

What Else Can The White Particles Be?

While white dust-like particles are usually one of the reasons mentioned above, it is worth saying that there are other possible options as well.

If the white particles are seemingly attached to the fish, the creatures might have an Ichthyophthirius multifilis infection (Ich disease).[6]

In case the white particles move, you should also consider worms. This may be the case if you have just added new things to your tank, including plants.

Fortunately, the solution is pretty straightforward. Vacuum the substrate and perform routine water changes.[7] The worms will gradually disappear:

An excellent YouTube video that demonstrates what aquarium worms look like and how to get rid of them.

If you found this article helpful, these may also interest you:


If your aquarium is covered in white particles, it may be due to a bacterial bloom, which usually occurs during the cycling process.

These bacteria will appear as small white particles. And when they break down ammonia and nitrite, you might even see a milky white substance forming.

However, white particles can also be debris that rose from the bottom during a water change or cleaning. It can also be air bubbles, which are completely harmless.