Why is my fish tank cloudy

why is my aquarium water cloudy

Why is my fish tank cloudy?

There is no denying that fish tanks, and aquariums make lovely conversation starters as well as unbelievable pets. There is something calming about watching fish glide through the water in their own time looking majestic and unaffected by the outside world.

Owning a fish is a responsibility though, as well as a science. Setting the right temperature, the right amount of food, making sure everything you place in the tank has been cleaned and doesn’t have any bacteria are all things you will need to consider.

One of the most frustrating, and upsetting things about owning fish though, is having cloudy water. Whether you’re wondering why is your new fish tank water green, grey or cloudy we have put together this guide to make sure you understand the in’s and out’s of clearing up dirty fish tank water.

Causes of Grey Water in my Fish Tank?

Too Many Fish

Getting your new tank and deciding on your new fish is an exciting time, and often you may be tempted to buy more fish than you need. They are fun to watch and soothing to be around, but buying more isn’t the best option.

You need to take into consideration the size of your tank, and the rate of your filtration. Fish, as well as decaying fish food and plants, will cause excess ammonia levels to rise in your tank. With excess fish, the levels of ammonia can increase quite quickly, and to dangerous levels.

Start slow. Choose a few fish and test your skills as an aquarium owner. Once your fish tank eco-system has settled, and you know more about keeping fish you can then go onto buying more, or more exotic types of fish.

Gravel Residue

In our experience, one of the most apparent reasons for grey or white water in a fish tank is due to gravel residue. When you first buy a fish tank, it is an exciting time, and you want to add in all sorts of fascinating décor to make it look amazing.

Before adding in those little touches though, you need to make sure everything is washed and cleaned properly. Adding contaminants to your fish tank can not only ruin the look, but it can harm your fish.

When washing aquarium gravel or ornaments, it is crucial never to use soap or detergents; they are harmful to your fish. To clean your aquarium gravel place it inside a colander and rinse it thoroughly, while stirring. Allow it to drain, rinse, and repeat until there are no contaminants or debris, and the water stays clear.


Bacteria or bacteria blossoms are the results of decaying plants or excess food. Bacteria blossoms aren’t harmful, and there are ways to remove them from the water with minimum problems.

When you set up a new aquarium, it can take up to a few months before bacteria can colonize and remove excess waste which may build up in the water. In this time, debris from decaying plants, or excess food can cause some cloudiness to your tank.

Once the bacteria have colonized, they usually take care of the excess waste, and you will not have any issues with milky water during that time though you can remove any dead, or decaying plants by hand. Any excess food can be removed, and you can reduce your feeding schedule to make sure all the food is being eaten and not left to rot.

Partial water changes will also help to remove excess waste from your tank and keep your water looking fresh and clean. In more extreme cases, you can use a flocculant, which allows debris to stick together and allows your filter to remove it, more effortless.

Dissolved Constituents

Once you have washed your gravel correctly, you may find you are still getting cloudy, or milky water. Another of the most stand-out reasons being dissolved constituents. Dissolved constituents can be silicates and other heavy metals which are found in water.

You can, and should, regularly test your water for any harmful constituent build-up which can harm your fish. Water condition is often enough to make sure your water is safe and fish-friendly.

Causes of Green Water in my Fish Tank?

Green water can be the bane of any aquarium owner’s life. The last thing you want when people admire your tank and costly fish is to be met with what looks like the bogeyman’s bathwater.

There is an apparent reason for green water, though; Excess algae.

You cannot stop algae growth, especially when you have live plants in your aquarium. But there are things you can do to help reduce the amount of algae growth and keep your water fresh and bright.

Too much light

Having a fish tank is amazingly relaxing, and as far as having a pet goes; they are a fantastic conversation starter when your fish tank is out on display.

You will want to make sure your tank is in the perfect place, though. Moving your tank isn’t easy. Once your tank is set, it is unlikely you will be moving it again for a very, very long time.

You want to set your tank near sunlight, but not directly. Having constant direct sunlight will result in excess algae growth.

Excess Nutrients

Regular water changes will help to keep your levels of phosphates and nitrates in check. It is the most used, and proven method to help improve the lifespan of your fish and keep your tank looking clean, fresh, and the center of attention.

Phosphate and nitrates can come from various sources. Decaying fish food or plants are both prime suspects when it comes to excess constituents. The only other obvious factor is the water you put in the tank.

It is essential to regularly check your water and tap water for levels of metals and contaminants

why is my New fish tank cloudy after a water change?

If you have a new fish tank and you notice cloudy water then don’t panic! There is an obvious reason for this, and as hard as it may be, the best thing to do is nothing.

When you add new water to your tank, there are microscopic organisms present which can affect the balance of the water. As the tank is fresh, the organisms which help combat cloudiness and break down excess waste in the water haven’t had a chance to multiply.

Given time they will multiply and outnumber the bacteria which causes the bacterial blossoms in the water. If you continuously try to add fresh water to the tank you will find your water will get cloudier; this is because you are disrupting the growth of the useful organisms and always adding new bacteria which will cause more cloudiness.

Letting your water ‘settle’ over a week or so will give the good bacteria a chance to multiply, and you will notice your water get less cloudy until it is clear.

Clean Fish tank FAQ

My Tank is Cloudy. What Should I Do?

Make sure you have a read through the above article. It covers all the main points you need to think about when dealing with dirty, or cloudy fish tank water.

If your tank is new, then don’t panic! Cloudy water is healthy, and often it takes time for your water eco-system to find a balance between good and bad bacteria. The last thing you want to do at this time is continuously change your water, thinking it will help or mess with your filtration.

Cleaning your filter when you are first settling in a new tank often results in you stopping, or killing all the good bacteria which is building up to combat the harmful bacteria spurs which are making your fish tank water cloudy.

Are live plants suitable for my fish tank?

For sure they are! Live plants not only make a fish tank look great, but they are hugely beneficial when it comes to balancing the ‘eco-system’ in the water.

Live plants are full of good bacteria and microbes, which help feed the water system. Live aquarium plants have more benefits including;

Nutrients – Live plants need nutrients to survive. They compete with bad bacteria found in the water, which will leave little food for the bad bacteria to grow.

Oxygen – We all know plants produce oxygen. Live plants in your fish tank will produce more oxygen, which will help break down waste; fish food, decaying plants, and dying bacteria.

How Often Should I Change my Fish Tank Water?

Once you are past the settling in phase for your tank, you should then incorporate regular water changes for your fish tank. Most aquarium owners will change out 25% on a monthly or less weekly to keep your water fresh and remove excess waste