Why is My Aquarium Water Cloudy- Reasons and Solutions

why is my fish tank cloudy - aquarium tales

Ever stared at your cloudy aquarium water in disgust? You are not alone. Cloud or milky aquarium water is one of the most common problems faced by both beginners and seasoned aquarists.

The good news is that there are some simple ways to diagnose and fix cloudy fish tank water. However, it is good to note there is no magic bullet solution. It will take you some little investigation to identify the cause and improvise an ideal solution.

In this article, we will walk you through some of the reasons your aquarium water is cloudy and how you fix them. Keep reading!

What Causes Cloudy Water?

Cloudy water can be a perplexing phenomenon for most aquarium hobbyists. Usually, the issue can be pinpointed to several fundamental causes related to your aquarium’s age and the level of care and maintenance you provide to your aquarium.

The ugly truth is that aquarium water doesn’t change so dramatically without a solid reason. Therefore, cloudy aquarium water means that you have done something unusual. However, you can easily solve the issue and prevent such happening in the future if you understand the mistake.

If you notice your fish tank water is turning milky white, it is a sign of bacteria bloom, which primarily happens during establishing the Nitrogen cycle process. Such a process will need time to solve. However, there are other reasons causing aquarium water cloudiness. Here are some of the reasons and their solutions.

Reason#1: Bacterial bloom

It is undoubtedly that this is the most common reason that might have turned your aquarium cloudy. Many hobbyists tend to experience this situation when setting up a new aquarium. It is associated with the early stages of an aquarium cycling process and usually appears as a milky haze.

One of the leading causes of bacterial bloom is decaying plants, uneaten foods, and fish waste because they offer a rich source of nutrients for bacterial growth. Apparently, your new aquarium water will become cloudy before establishing bacterial colonies that can clear the waste from the water.

Although the situation can be baffling, you should not worry much about having bacteria growing in your fish tank. Bacteria is very useful in breaking down the waste and maintaining healthy water conditions; therefore, striking a balance between fish and microorganisms will keep chemicals under control.

However, water quality suffers when the bacterial colonies can’t do the job well. That is why bacterial bloom is common in new aquariums that are not appropriately cycled.

Bacterial bloom can also be caused by often turning off the filter of your fish tank. Ideally, it is good to turn off the filter on rare occasions, but if you get accustomed to shutting it more frequently, for instance, every night, you may end up seeing milky white water after a few weeks.

You shouldn’t also change plenty of water because it creates a mini-cycle as the bacterial colonies re-populate.

Besides, adding untreated water when performing water changes can result in cloudy aquarium water. This is because untreated water may contain harmful chemicals like chlorine, which kill the beneficial bacteria colony; therefore, creating an imbalance between microorganisms and ammonia plus nitrites produced.

How to clear up bacterial bloom

If your aquarium is new or performed massive water changes, all you need is to allow your fish tank a few days, and it will settle. Typically, the cloudiness will disappear in 2-3 days. Nevertheless, it is good to test all other factors with high-quality equipment to ensure they are at requirement levels. Remember that you can spike ammonia and nitrite levels during the Nitrogen cycling process.

If you believe the milky white cloud water is caused by other factors like the accumulation of excess waste, you will need to take immediate action. Remove the decaying plants and uneaten foods. You might need to vacuum the gravel frequently and perform partial water changes.

Reason#2: Overstocking

There are many issues associated with overstocked tanks. Besides stress and behavior clashes, having plenty of fish in a single aquarium can spike ammonia and nitrite; therefore, deteriorating the water quality and, consequently, the environment. An excessive amount of ammonia and nitrite is toxic and potentially lethal for your fish.

To understand this issue properly, you will need to consider your aquarium as a small ecosystem – a very tiny lake. Your fish tank has a filter(s) that does the same as streams and springs to clean and aerate your ecosystem. There are also microorganisms that help break down waste; therefore, keeping the harmful chemicals under control.

With such thinking, you will surely add the right number of fish to the tank. Remember introducing large quantities of fishes into the tank means heavy feeding, which also deteriorates to a toxic environment. Since your ecosystem is closed and you can’t enjoy the lake’s benefit of continuous freshwater supply, you will have to immediately intervene if you notice any abnormalities.

How to fix cloudy aquarium water in an overstocked fish tank

The ultimate way to fix a cloudy fish tank water wrestling from overstocking is to keep the ideal number of fish required for the particular aquarium. It is advisable you introduce fish into your aquarium gradually as you monitor for such occurrences. If you notice any milk haze, it is time to stop and check if you are overstocking your aquarium.

If it is impossible to keep the number of your fish low, you will have to over-filter your tanks and perform more frequent water changes. Keeping an aquarium that is heavily planted can also help to minimize cloudiness resulting from overstocking your tank.

As usual, you will have to perform water changes and vacuum the gravel while looking for ways to relocate some fishes. Once everything balances, your will aquarium will regain its healthy state.

You may want to allow your fish tank about 3-5 days to settle.

Reason#3: Overfeeding

If you feed your fish too much or too often, you risk getting cloudy aquarium water. Remember that the uneaten and decaying foods provide an ideal environment for the growth of bacteria. If you overfeed your fishes, the water cloudiness can result from food particles suspended/dissolved in the water or bacterial broth.

Apparently, you will find that manufacturers of different fish foods indicate that you feed your pets several times per day. If you follow these instructions, especially for beginners with new aquariums, you must regulate the amount of food you are giving the fish.

Besides, you need to know how to handle the fish food that drifts to the bottom of your tank. Basically, uneaten food will decay, and if the quantities are high enough, it will cause water cloudiness.

This issue is very rampant in betta sororities because bettas don’t eat lots of food. If you keep bettas, you will need to be extra careful with the amount you feed your fish because it is very easy to pollute the tank.

overfeeding fish

How to eliminate water cloudiness resulting from overfeeding

Here, you will need to partially change the water and vacuum the substrate. This will help clean the water; therefore, creating a safe and healthy environment for your critters. After cleaning, you will want to evaluate your feeding pattern so that you prevent such a problem from occurring again.

Although instructions on fish-food containers tell you to feed your critters multiple times in a day, it is advisable you feed them once and even allow them fast once per week. This is not only healthy feeding but also keeps your aquarium cleaner.

Besides, keep in mind that what goes into the fish will eventually come out. Therefore, overfeeding means more waste in the tank on top of the decaying, uneaten food.

Reason#4: Algae bloom

Seeing cloudy green water in your aquarium is a no-brainer – it is caused by algae growth. If you have owned an aquarium for whatever time, the chances are that you are aware of algae problems. These plant-like organisms will grow in your fish tank, and if they go unchecked, they can turn messy.

It is unfortunate that algae thrive in conditions like those of plants. Therefore, if you notice algae blooms in your aquarium, it signifies that there is too much light or excess nutrients or both in your fish tank. The presence of phosphates or nitrates is a serious cause of green water.

  • Too much light: One of the significant reasons you see frequent algae blooms in your aquarium is due to the placement of your tank. Placing your tank in a spot where it is hit by direct sunlight or leaving the lighting system for considerably longer will result in algae growth. Fortunately, this is one of the easiest to cure.
  • Excess nutrients: Nutrients such as nitrates and phosphates gives algae added energy to keep growing. A sudden spike in these nutrients can result in water cloudiness. The possible source of such excess nutrients is decaying uneaten foods and dead fish, fish waste, and water source. If you do not control the spiking nutrients, algae will suddenly increase; therefore, upsetting the aquarium balance and adversely affecting your critters.
algae bloom

How to solve the issue of algae bloom in aquarium water

Getting rid of algae bloom can be one of the most challenging issues until you identify the cause. The prime solution of algae bloom is to perform water changes and remedy whatever the cause of the bloom. If algae bloom is resulting from excessive lighting, you will need to move your tank to a spot where there is no direct sunlight and/or control the lighting system.

You will need to get control of your feeding practices if algae bloom is caused by nitrogen spikes. However, for nutrients like nitrates and phosphates, it is extremely important to address them at their source.

To get rid of phosphate, use Ro water or phosphate remover to treat water before pouring it into the fish tank. Since nitrates primarily come from fish waste, ensuring your filter is clean will keep them under control.

Reason#5: Unwashed or insufficiently washed gravel

If your aquarium water turns cloudy immediately or within two hours of setting up the fish tank, then it is that you forgot to wash your substrate or didn’t wash it sufficiently. Usually, sand and gravel substrates have fine dust-like pieces that you can’t notice with naked eyes. These specks will separate from the large pieces of substrates and float.

Unwashed gravel results in a very ugly haze, but it is effortless to solve.

How to get rid of cloudy aquarium water

If your aquarium is pretty new and you haven’t added any livestock, drain the tank and rinse the substrate until water runs clear. This will completely resolve the issue.

You will have to perform a partial water change for an aquarium with life, and the problem will be contained. You can also allow it 1-2 days, and your filter will eventually trap most of the floating dust. Because it is likely for some particles to settle at your tank’s base, you will need to vacuum the gravel to solve the problem completely.

Reason#6: Driftwood leaching tannins

This is the last cause of water cloudiness on the list. While all other causes of cloudy aquarium water are directly associated with your care and maintenance mistakes, driftwood leaching tannins is absolutely not your mistake. Instead, it may be due to minimal knowledge of your tank decorations.

While adding natural driftwood to your aquarium is a great idea, it can give your tank an unpleasant look. Natural driftwood does not only look fantastic but also lowers water pH and offers a spot where your fish will be nibbling and rasping.

However, you may notice your fish tank water is turning yellowish a few days after introducing driftwood into your aquarium. This is because of driftwood leeches tannins, which dyes the tank water.

The good news is that the tannins are not likely to hurt your critters. So, what do you do if you don’t like the yellowish tea-like color, but you would like to have the driftwood stay? Here is the solution.

How to remend driftwood tannins

The main reason why driftwood leaches tannins is that it was not pressure-treated properly or it is too soft. To solve the problem, you will need to replace the wood with one that has been boiled upfront.

If your wood is too large for boiling, you can soak it in a large storage container for a few days before you drop it into your aquarium. Ensure the container is free from detergents and chemicals.

The carbon in the filter will help with this, as well. When paired with regular water changes, the water will clear up in the next few days. Because tannins are leached over time, you are sure that the issue will end soon.

You should also keep an eye on the pH value so that the tannic acid does not lower the pH excessively.

How to Prevent Cloudy Aquarium Water

From the above causes and solutions of water cloudiness, you can do pretty basic things to avoid cloudy aquarium water disappointments. Here are some ways to prevent such situations.

Step-1: Wash the substrate thoroughly

Make sure you wash the substrate thoroughly before adding it into the fish tank. This will remove the dust-like particles which give ugly haze.

Step-2: Do not overfeed your fish

Beginning hobbyists fear their critter might starve to death and therefore end up feeding them heavily. Because there are few bacterial colonies, the cloudy water bacteria takes advantage and multiplies faster, giving the water milky-white color.

At worst, the level of ammonia and nitrites starts to rise. As advised above, feed your critters once per day and allow them one day to fast.

Step-3: Add activated carbon media to your filter

Activated carbon media absorbs the nutrients feeding bacterial bloom; therefore, keeping the fish tank water clear.

Step-4: Do not overstock your aquarium

Huge quantities of fish mean more waste and more food. Regardless of how good your filter is, this will likely spike the ammonia and nitrite level to uncontrollable levels in addition to turning the water cloudy.

Step-5: Don’t place your aquarium in direct sunlight

Direct sunlight exposure promotes the algae bloom. It is better to avoid placing the tank in direct sunlight. Well lightened room is okay, but don’t put it close to the window, on the balcony, or the veranda, where sunlight comes directly.

Step-6: Seed the aquarium water

If you access another healthy and well-established aquarium, you can get a few handfuls of the substrate from that aquarium and add them into your fish tank. You can also get some seeding equipment like cartridge filters and bio-sponges to help keep biological balance in your ecosystem.

Step-7: Keep up with tank maintenance practices

Regularly keep the ammonia and nitrite levels tested. Also, don’t overlook the benefits of changing your aquarium water regularly.

Take Away

Does the water of your brand new tank turn cloudy a few days after staying clear? For both beginners and pros, it is usual to get busy and neglect some aquarium maintenance tasks.

This doesn’t mean all is lost. With the above remedies on each cause of cloudy aquarium water, you will be able to restore the excellent state of your tank and give your critter a better environment.

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Sujit Modak Aquarium Tales Owner
Sujit Modak

Hello, everyone! Welcome to my aquarium blog. Fishkeeping is my passion, and I started this fascinating hobby back in 2006. Besides my engineering profession, I deeply studied many fishkeeping topics since I started building my home aquarium. I researched effective aquarium filtration and lighting of planted aquariums. I am keeping 20+ species of freshwater and saltwater fish as my aquatic pet collection. I successfully experimented with a complex ecosystem inside the aquarium, biotope aquariums, aquaponics, etc. I would love to share some learnings from my hands-on experience of the last 14 years. Hopefully, my sharing will be somewhat helpful to make your aquarium journey awesome! 

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