Reasons for white cloudy water in aquariums and possible solutions

Is your aquarium water white and cloudy? Are you not sure whether this is something you should worry about? Most people without experience would probably freak out if they started a new tank, added a few fish, and bang—one morning they woke up and the aquarium water was all in a white fog.

White foggy aquarium water tuned into clear water

But there really is no reason to worry when this happens, since this is not a big problem and can be solved easily. Actually, in many cases it might even go away on its own.

Reasons for white cloudy water in aquariums

There are two common reasons for foggy water in an aquarium, and the good news is that neither of them are dangerous.

  • The most common reason for white cloudy aquarium water is bacteria bloom, or a rapid growth of bacteria. Bacteria does not necessarily mean anything bad is happening. As you might know, bacteria are everywhere, and aquariums actually rely on the presence of bacteria to run properly, as they help to break down waste products created by your fish and plants. These little guys are called beneficial bacteria; they grow on aquarium filter media, in gravel, and on decorations and other surfaces. The waste products created by fish are nutrients for beneficial bacteria, and the waste products of bacteria are, in turn, nutrients for plants in the aquarium. Sometimes as new fish are added to a tank, bringing new nutrients for bacteria, the bacteria can start to grow in extreme speeds and therefore make the water cloudy.
  • The second most popular reason for hazy aquarium water is insufficient cleaning of new gravel. New gravel is covered with dust and has to be rinsed before being placed inside a fish tank. If you do not rinse the gravel, all those dusty particles will float up as you fill the tank and make it look cloudy.

How can you tell what is making your tank water cloudy? If you recently added gravel, it could be either of those reasons, because new gravel is also a perfect place for bacteria to grow. Normally, if the water is cloudy because of dust from the gravel, it will settle in less than a day. If it stays cloudy longer, it is most likely a bacteria bloom.

What to do if aquarium water has become cloudy

If you concluded that your water is foggy because of bacteria (the most common cause), then there is nothing much to do—the water will become clear within two to three days. You can, however, check the oxygen level in your fish tank. There’s no need to test—just check whether the fish are gulping for air, moving their gills rapidly or are becoming inactive. If you see any of those signs, you can turn the air pump on for a prolonged amount of time or replace part of the water by using a bucket to remove a portion and then dumping in some new water.

If, however, you suspect that the root of the problem is insufficient cleaning of the gravel, you can opt to remove the gravel, rinse it and then put it back. It’s a lot of work, but it will make the aquarium environment much friendlier. It’s fine to leave it in and wait until white dust particles settle down and the water becomes clear; however, keep in mind that the water will become foggy each time you partially replace water or rearrange the gravel, though the effect will fade over time.

So, while it may look concerning, we cannot stress enough that, in most cases, cloudy water is not a problem for aquarium inhabitants. As long as they have enough oxygen, your fishy friends will be fine and the water will soon become clear with no damage done.