Why is My Aquarium Water Cloudy?

Everyone enjoys watching beautiful tropical fish swim and explore the aquarium. The swaying aquatic plants and interesting aquascape can make you feel like there’s a piece of an Amazonian river or African lake right in your own home. But cloudy aquarium water can give the tank a dirty, murky appearance.

The truth is, nearly all aquarists wrestle with cloudy water sometime, no matter how experienced they are. It can be very frustrating, leading some new aquarists to abandon the hobby.
The good news is cloudy water isn’t impossible to cure. But there are specific types of cloudy aquarium water, each with its own cause and cure. Fighting a cloud requires knowing what caused it. Otherwise it will keep coming back! Want to know more?
Here’s what you need to know to keep your aquarium sparkling clear!

Many aquarists can’t identify the substance that is causing murky aquarium water. This leads to frustration when attempts to clear up the water fail.
It’s possible to take drastic measures, like draining the aquarium, washing the gravel and ornaments, refilling the tank and having the cloud form again.
The slogan “knowledge is power” is especially true when trying to solve aquarium issues. You can spend a lot of time and money needlessly by misdiagnosing a cloudy water problem.
We’ll identify the various symptoms and causes of murky aquarium water, so you’ll know what is causing the problem in your tank.

Before trying to fix a cloudy aquarium, it’s important to train yourself to mentally describe what the water looks like.
This is important because it will allow you to identify what is causing the unsightly water condition.
Here are the three main visual categories of cloudiness in the aquarium

It is possible to have “clear” water with a color tint. Imagine a glass of iced tea. You can see through the liquid, but it has a brown color.

“Cloudy” means the water has something suspended in it that obscures the fish, plants and reduces light penetration in the tank.
Some cloudy water is like pea soup. It’s so thick you may not even be able to see your fish! Now let’s take a look at each type of cloud and discuss what it is, what caused it and how to fix it.

The most common water discoloration, often described as a cloud, is water with a green tint to it.
Green water, as it’s called, is caused by millions of tiny green algae cells floating around in the water. The green algae, when in high enough numbers, will make the water have a greenish color. You can still see through the tank, but it looks swampy.
Here’s something to consider. Crystal clear aquarium water is teaming with algae cells. It’s only when they become so great in numbers, that they affect how you see your aquarium.
Water changes may help if you’ve got a build up of nutrients in the aquarium.
Dilution is a great way to stave the algae.
Over feeding can also stimulate the algae, causing a green tint to the water. Cut back on the amount and frequency of feeding. Uneaten food should never be seen in the aquarium. Keep the aquarium light on for no more than 10 hours.

The second most common discoloration is caused by a build up of organics in the water.
Algae, fish waste and other natural substances will accumulate in the water. They give the water a yellowish or brown tint, like weak tea.
It’s easier to see the color when the light is turned off and you look through the aquarium. Yellowish water is a sign that organics are accumulating in the tank.
A dirty aquarium with organics tends to be a “sick” tank. The neglected water quality affects fish health. Disease causing organisms thrive in organic rich aquariums. Dirty water increases the likelihood of disease problems.
Water changes along with a light siphoning of the gravel bed will dilute the organics. Using activated carbon to adsorb organics will keep the water crystal clear.
Be sure to change the activated carbon every three to four weeks.

Aquarium water with a reddish or pink tint is usually being over fed.
The colors used in the food formula will “bleed” out into the water, giving it an unnatural color. Brightly colored foods that are uneaten and decaying in the tank will cause this problem. While water changes will help, you must reduce feeding if it is the cause of this kind of “cloud” problem.

If you’ve just set up your aquarium and added water, there is usually a slight cloudiness to the water. This is caused by residual dust on the gravel.
Colored or epoxy coated gravel are usually very clean. Natural sand, gravel and dolomite can be dusty and cause murky water.
In time the dust will settle.
An aquarium filter with fine mesh mechanical filtration sponges or fiber floss will help clear the water.

Sometimes a very dirty tank will suffer from floating particles. The tan or black debris are comprised of uneaten fish food, solid fish waste and bacterial slime.
Aquariums with a heavy fish load or large fish, like cichlids, can have this type of cloud problem.
A gravel siphon is helpful for removing solids on and in the gravel. You may need a more powerful aquarium filter to keep the solids suspended so they can be pulled into the filter. Remember to change the filter media frequently if there are a lot of solids in the tank.
If not, the organic matter will decompose inside the filter, releasing algae promoting nutrients into the water.

A temporary cloud is normal for new aquariums. Everybody experiences it. Just let nature take care of it.
Chronic discolored water is a sign of poor care or an imbalance of food, nutrients or organic waste.
Proper maintenance of the aquarium filter is very helpful. But for long-term health and stability of the aquarium, a proper balance of feeding and fish load must be achieved to keep the water clear.
Resist the urge to add more fish or another serving of food and you’ll find your aquarium water stays crystal clear!