5 Reasons A New Tank Is Cloudy With Fish After 1 Day

Setting up a new fish tank can be an exciting experience for many. But the aquarium water can turn cloudy pretty soon for a host of different reasons and can leave you wondering what you did wrong.

If you notice that your new tank is turning cloudy after just 1 day, don’t be disappointed. There can be many reasons behind this, including a bacterial bloom, residue from the gravel/substrate, an inadequately cleaned tank, bad water conditions, and algae growth.

Read on to discover more about why your new fish tank might be turning cloudy after just 1 day. Happy reading!

Why Is My Fish Tank Cloudy Without Fish After One Day?

Here, we list down some of the reasons why your fish tank may be cloudy after one day when you don’t have any fish in it.

1. Residue From the Gravel

The gravel or the substrate that is used in fish tanks has the potential to turn the water cloudy. If it isn’t washed properly before putting it into the tank, it can quickly turn the water cloudy within minutes. A sign that residue from the gravel is making your tank cloudy is that the water quickly turns grey or dark brown. 

2. The Water Is Not at the Correct PH Levels

Another reason your fish tank might be cloudy is if the water conditions are not what they should be. This usually means that the water has a lot of dissolved metals, and its pH is quite high. This may also be the case when you use tap water. To check if the water conditions are making your tank cloudy, get a water test kit and test your tank water.

3. Bacterial Bloom Due to New Filter

A bacterial bloom may be the cause of cloudy water in your fish tank if you’ve either used a new filter in the same filtration system or started the existing one after a long time. This happens because the old beneficial bacteria die off, and the new ones start to grow. This usually turns the tank water cloudy or milky. The water may also turn cloudy if you’re using a new filter medium.

4. Bacterial Bloom Due to New Bacteria Growth

The beneficial bacteria in your tank can die for several reasons, including changing water conditions. When these bacteria start growing again, they can turn your tank water milky. This usually happens when the water conditions have returned to normal. Your tank water turning milky is a sign that the beneficial bacteria have started growing.

5. Algae Growth

The algae growth can also be responsible for turning your tank water cloudy. In this case, the tank water becomes cloudy green. Algae growth is usually caused by direct exposure to sunlight or any other source of light. Since algae is a plant, more sunlight means more growth. Algae may also grow quickly in certain circumstances and can turn your tank water cloudy even if you don’t have any fish.

dirty aquarium with water tree and fish inside wating cleaning

Why Is My Brand-New Fish Tank Cloudy Without Fish?

Now, have a look at some reasons your brand-new fish tank may be cloudy, even when you haven’t put in any fish.

1. The Tank Is Not Properly Cleaned Before Filling It Up

This is one of the very simple reasons your brand-new tank might be cloudy. People who’re new to fishkeeping usually make this mistake, although this is very easy to avoid. Your new fish tank might have dust and grime on its inside walls, so washing and drying them properly is absolutely necessary before you start filling up the tank with water.

2. The Water Is Not Clean

Another reason your brand-new tank may be cloudy is that it is not filled with clean water. If the water contains impurities, then it can easily make your tank cloudy when you fill it up. This usually happens with tap water. To avoid this mistake, get your source of water tested to determine if it’s clean enough to be used as tank water.

3. Residue From the Gravel/Substrate

This is one reason we’ve discussed previously. If you put gravel in your new tank without first washing it properly, it will certainly make your tank cloudy as dust and grime spread throughout the water. To make sure this doesn’t happen, wash and clean the gravel before putting it into your new tank. Or, if the water is already cloudy, drain it, remove the gravel and wash it properly before replacing it and refilling the tank.

4. Addition of Driftwood

If you’ve bought a new fish tank, you might want to put in some decorations. Driftwood is a popular choice as a decoration among those setting up their fish tanks. It looks great, and plants can grow on and around it, and fish can use it as a hiding place. But driftwood can sometimes make the water milky and may lower its pH as well.

5. Using Chemical Additives

If you’re setting up your brand-new fish tank, putting a lot of chemical additives in the water might not be a good idea. The reason for this is that those chemicals might react with something in the water, such as the decorations, and can make the water cloudy. To determine what is reacting with those chemicals, you can do a series of tests and then remove that item.

How Do I Fix Cloudy Water In My New Tank?

Here are a few ways to fix cloudy water in your brand-new tank.

1. Test the Tank Water

Many problems that make your tank water cloudy can simply be fixed if you test your tank water and clean it accordingly. If the water has a lot of nutrients, then replacing the water or waiting for the nutrient balance to establish might work. Or, if the cloudy water is caused by residue from gravel, then removing the gravel and washing it before putting it back into the tank might work.

2. Seed the Tank

To tackle cloudy water and re-establish the nutrient balance in the tank, adding gravel and bio sponges and wheels might help restore the balance and encourage the growth of beneficial bacteria. Usually, these are taken from established aquariums and can thus help other tanks. This way, the water will get cleared faster.

3. Replace the Tank Water Regularly

Replacing the tank water is absolutely necessary in order to maintain a healthy ecosystem in your tank. Once your fish tank is established, replace one-third of the tank water every week. The tank water can often become cloudy due to residue from gravel or reactions caused between the water and driftwood. Hence, replacing some of the tank water can help speed up the clearing process.

4. Scrape off the Algae

A buildup of algae is a major cause of cloudy water. Although it doesn’t mean the water is impure, it does make your tank look dirty. The algae usually build up on the inside walls of your tank and can make the water cloudy green. The inside walls of the tank should be scrubbed regularly, and the algae should be removed by an algae scraper.

5. Use Chemical Filters

If your tank water becomes cloudy due to decorations such as driftwood, then using chemical filters might be a good idea to fix that. Driftwood can add tannins — that are certain chemical molecules — to the water and can change its color to a cloudy brown. Chemical filters such as activated carbon can absorb these chemicals and prevent that from happening. But they should be replaced frequently.

6. Wait

If your tank is becoming cloudy due to a bacterial bloom, then the best solution might be to just wait and let it clear on its own. Avoid adding chemicals to clear away the cloudiness. The water will clear after a while, and the bacterial balance will be re-established.

How Long Does It Take For A New Fish Tank To Clear Up?

Watching your new fish tank turn cloudy can be disappointing and worrying. Depending on what is making the water cloudy, the time it takes to clear up can vary greatly. This is because many factors can cause cloudiness. In many cases, the cloudiness is temporary and will clear up on its own after a while. If the cloudiness is caused by the growth of beneficial bacteria, then it may take a few days for the water to clear up.

If the cloudiness is caused by certain chemical reactions, then diagnosing and fixing the problem may take some time. Besides that, if algae and dirty water conditions are the sources of cloudiness, then the water won’t clear up by itself. You’ll have to scrape away the algae and replace the water, respectively.

How To Prevent Cloudy Water In Your New Tank

There are a few things you can do to prevent your tank from becoming cloudy. Keep reading to find out about them.

1. Wash Your New Tank Thoroughly 

This is a no-brainer. When you buy a new tank, it is quite important to thoroughly wash it in order to remove any dust and grime. Wash both the inside and the outside of the tank and dry it before filling it up with water.

2. Use Clean Water

Using clean water in the first place is important to prevent the water from becoming cloudy later on. Make sure the water you fill the tank up with is clean and doesn’t have any impurities. This can be determined by doing a water test.

3. Wash the Gravel/Substrate

As we mentioned previously, washing the gravel is important so that it doesn’t spread any mud into the water. Wash the gravel and any decoration that you want to put in the tank thoroughly.

4. Avoid Putting the Tank Into Direct Sunlight

Putting your water tank into direct sunlight or near any other light source can allow algae to grow easily since photosynthesis can occur more freely. Algae is a plant, and like all plants, it too grows using photosynthesis. The algae growth, in turn, will turn your water cloudy green in color.

5. Avoid Adding Chemicals Without Knowing About Their Impact

Adding any chemical additives to make your water healthier can have unintended consequences. The chemical may react with any decoration, and that can make the tank water cloudy. So, if you don’t fully know how the chemical will react with other items in the tank, avoid adding it to the water.

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Frequently Asked Questions (FAQs)

How Long Will A New Tank Stay Cloudy?

The most common reason for a new tank becoming cloudy is the initial growth of beneficial bacteria. Besides that, the water also establishes a balance of nutrients and gases, and these processes tend to make a new tank cloudy for a temporary period. This article explains this phenomenon in more detail, referring to it as “new tank syndrome.” The water usually clears away on its own after a couple of days once the water has become stable.

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How Do I Make My Aquarium Water Crystal Clear?

Having an aquarium with crystal clear water is a dream for fish keepers and hobbyists. Who doesn’t like a crystal-clear aquarium? Since there are many reasons why your aquarium’s water might become cloudy, there are also lots of solutions for making the water crystal clear. In this guide, we’ve mentioned the ways in which you can ensure that your aquarium water remains clear. Give this guide a read too, to learn more about keeping your aquarium water clear. Always remember that whatever the reason for the water’s cloudiness, you can definitely make it crystal clear, provided you put in the required care and effort.


Although it can be disappointing to see your new fish tank turning cloudy after just 1 day, it is important to diagnose the problem so that you can work on its solution. This guide mentions many different reasons why your tank might be turning cloudy and includes solutions to those problems to help you fix them.