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Why Is My Fish Tank Cloudy And What To Do?

Dealing with a cloudy aquarium can be a frustrating experience, especially when you have no idea what caused it in the first place. But once you are able to identify the actual reason for the discoloration, getting rid of it becomes easy.

What Causes Cloudy Aquarium Water and How To Clear It?

why is my fish tank cloudy
The cloudiness in aquariums can be caused by many things, including a dirty substrate, inadequate filtration, bacterial blooms, algae blooms, or tannins. It could even be a case of biofilm that has formed on the glass, making your tank looks hazy.

The most efficient way to clear cloudy aquarium water is to apply a solution based on its color or appearance. Once you can tell what it looks like, feel free to take the appropriate measure discussed below.

Particles In The Water

Can you see little particles floating in the water? If yes, the cloudiness in your aquarium is a result of one of the following causes:

Dirty Substrate

After filling up an aquarium, if the water column gets clouded by dirt particles, it’s probably due to the debris-attached substrate.

In this case, you can wait for the dust particles to settle down or get collected and removed by the filter. The murkiness should be gone within a few days.

But if the situation isn’t significantly improved even after a week, perform large water changes or drain the tank and rinse the substrate until the water runs clear.

Inadequate Filtration

Your aquarium contains fish poop and uneaten food particles; if your filter isn’t removing that waste, it will end up in your water column.

There are three conditions for inadequate mechanical filtration:

  • Your filter is small for the amount of bioload your tank produces. The particular matter has no option to leave the tank by itself, so it will end up floating all over the water column.
  • Having the right-size filter but with the wrong media will also lead to murky water. A filter media with bigger pores will allow more matter to go through it and back into the tank. For example, filter floss catches more gunk than a coarse sponge.
  • When you don’t clean your filter media regularly, it can get clogged up, resulting in reduced efficiency.

To remove the aquarium water cloudiness caused by solid waste particles, perform daily water changes, siphon the substrate, and if you haven’t cleaned your filter in a while, take out your filter media and rinse them until all slit is removed.

Messy Fish Food

Certain fish foods are loosely bound and tend to break apart easily, creating a cloud of dust in the water column.

Bacterial Blooms

Does it seem like someone has poured a spoonful of milk into your tank? An aquarium with bacterial blooms gives off the appearance of diluted milk and has no visible particles floating in the water.

When you have excess nutrients in the tank but insufficient beneficial bacteria to deal with, the heterotrophic bacteria will populate rapidly, resulting in reduced clarity and milky water.

Bacterial blooms can occur during the early stages of the tank cycling process. If you add fish into an aquarium before it’s fully cycled, the bacteria will get a sudden dose of nutrients to bloom and thus cause cloudiness in the water column.

Anything that releases excess nutrients in the water and causes an imbalance – such as overfeeding, overstocking, or a dead fish – is a contributing factor to bacterial blooms in fish tanks.

To get rid of bacterial blooms, reduce the amount of food being fed to the inhabitants, and make sure there is no dead fish in the tank. If the bloom occurs in a newly set up tank, do not add more fish until the haziness is gone.

Most importantly, refrain from doing water changes, using UV sterilizers, or any medication because it may worsen the condition. Instead, wait a week or two, allowing the beneficial bacteria to colonize and help dissipate the cloudy water.

Green Water

If your aquarium water seems green, it’s due to the overabundance of single-cell algae. It’s a tiny, floating algae that blooms from excessive light, nutrient imbalance, and higher nitrate levels.

To get rid of cloudy green water, first, determine its cause.

Below are few causes with solution:

Cut down on light

When an aquarium gets exposed to higher intensity light and/or longer duration of light, algae blooms are inevitable. So the first thing you have to do is reduce the amount of light.

The less light your tank gets, the faster the cloudiness disappears.

  • If you have a planted tank, keep your lights on for not more than 8-10 hours. For a plantless tank, keep the lights on only during feeding hours.
  • Make sure your aquarium isn’t under direct sunlight.
  • If you want faster results, black out your aquarium for at least 7 to 10 days
    by wrapping it up with a blanket.

Control nitrate in your aquarium

Higher nitrate levels are the main culprit for green water in aquariums. We want the nitrate concentration to be 20 ppm or less.

To bring down the nitrate levels, you should vacuum your tank gravel and perform water changes.

Also, make sure your tank isn’t overstocked. The more the bioload, the higher the amount of nutrients/food for the algae microorganism to flourish and make the aquarium water look like pea soup.

Perform UV Sterilization

The fastest way to get rid of green water is UV sterilization. When the water passes through UV rays, it changes the cell structure of the microorganism, preventing it from reproducing.

UV sterilization accompanied by water changes will clear the cloudiness in less time. However, the algae will come back if you don’t eliminate its source. Getting rid of the underlying issue is a must.

Get floating plants

Floating plants block the light and outcompete the algae for nutrients starving the green-water-causing microorganisms to death.

Water sprite, waster wisteria, guppy grass, and hornwort are some of the best low-teach plants you can easily get from your local fish store.

Brown Water

If your aquarium water has a brownish or yellowish tint, it indicates the presence of tannins – an organic compound naturally found in driftwood, catappa leaves, and other aquatic botanicals.

Tannins leaching into the water column not only cause discoloration but also lowers the pH.

  • To get rid of brown water in your tank, do a few small water changes and use activated carbon or Seachem Purigen.
  • If you have driftwood, boil it or soak it to remove the tannins quickly.

Biofilm on Glass

It’s not always an issue with the water quality. Sometimes, the biofilm formation on the glass gives the aquarium a somewhat cloudy appearance.
To clean your viewing panels, give them a good scrub using an algae scraper.

Final Words

Apart from being an aesthetic issue, cloudiness is also an indicator to determine how healthy the water is for the inhabitants.

Cloudy water is not harmful to the fish unless left untreated for a prolonged period.
We hope, by now, you have a better understanding of all the possible causes of cloudiness in an aquarium and the ways to remove it.