Why Is My Aquarium Water Cloudy?

Cloudy water in your aquarium can be a troubling sight to see, but it is a phenomenon that is very common in the aquatic world. Unfortunately, there isn't a single cause for cloudy water, but there are ways of diagnosing where the problem may lie.

Before diagnosing the problem, you should be sure to check that you have your fish tank correctly setup.

Basic Checks

Firstly check you are running an adequately sized aquarium filter; as this is the heart of any aquarium setup. If your filtration is in good order, the fish tank will thrive and you should typically not see any cloudiness at all.

Next, be sure that your aquarium is not overcrowded with fish. Having too many fish in an aquarium can lead to many problems, and can cause unwanted fatalities along with causing a lot of strain on your filter system. On the same subject, it is also important not to overfeed your fish as this creates a lot of waste which your filter may not be able to deal with which can cause cloudy water.

Finally, be sure that you are keeping up with regular water changes and general aquarium cleaning. This helps keep your aquarium clear and will help cycle out excess waste and debris lurking in your water.

New Aquarium Setups

So you have just set up a brand new aquarium. You've put in your gravel, lovely new ornaments and decoration pieces, but as you fill up your tank with water you notice the water has turned cloudy. What would cause this to happen?

Well, a common cause for cloudy water is using gravel and aquatic ornaments that have not been thoroughly rinsed before being put into the aquarium. Bags of gravel and ornaments typically carry a lot of dust, chemicals and debris leftover from when they left the factory, so it is important to give them a thorough wash before placing them into your new aquarium.

The Early Stages of Biological Filtration:

During the early stages of owning a new aquarium, cloudy or milky water can arise due to the fact that your biological filtration setup is still establishing itself. This is sometimes known as "Bacterial Bloom".

This cloudiness is beneficial bacteria multiplying rapidly in order to tackle the ammonia and other waste being produced by your fish in the tank. This is particularly common with newly installed filtration setups.

This is not something to be worried about, and it is important to be patient during this time. Usually, an aquarium will be able to sort itself out once the filtration system has been properly established. Keep on top of doing water tests, and maintain doing regular water changes as well to help this process resolve itself.

If you require a Water Test Kit, you can find them here:

Adding New Fish

When adding new fish, it adds extra strain to your filtration system because of the extra food debris and organic waste that gets produced. This can cause the aquarium to become cloudy while going through another bacteria bloom, as the filtration system adjusts to the new additions.

Over time, the biological filtration will adapt to the new additions, and this will usually resolve itself without a problem. It is still important during this time to monitor the chemical balance using water test kits and to stay on top of your water changes as well. Changing about 10-15% of the aquarium water twice a week is usually best, and like before, patience is the key.

If you find that your aquarium is not coping well with the new fish, you may want to look into treatments such as "Pure Aquarium Bombs" by Evolution Aqua, which can help combat water quality emergencies. 

If you are adding or intending to add fish to your aquarium, you can find more information and care tips in our blog post; "How Many Fish Can I Put In My Aquarium?", which can be found here: