Causes and Solutions of Cloudy Aquarium Water

When it comes to fish keeping, cloudy water is inevitable regardless of whether you are a pro or beginner. It is one of the most frustrating things that can happen in your aquarium.

But why should we talk about this issue? First, cloudy water diminishes the appearance of your aquarium. No fish keeping owner would want an aquarium with cloudy water. Secondly, cloudy water can be an indication that the water is unhealthy for your precious fish.

In this guide, we will examine some of the main causes of cloudy water in the aquarium and their solution. Continue reading if you want to diagnose the problem.

Potential Causes and Solutions of Cloudy Aquarium Water:

  • Gravel or Substrate Residue can make the water cloudy:

Introducing various substrates on your aquarium can make the water cloudy unless you do it carefully. One of the most common substrates that many fish keeping owners choose is the gravel.

So if your aquarium water turns cloudy within an hour or a day, it can be due to inadequately cleaned gravel.

Solution: Proper Cleansing of Substrates

Typically, this kind of issue will resolve on its own with a few days unless the added substrates are significantly dirty. However, if it prolongs, then we recommend draining your aquarium and rinsing the substrates with clean water thoroughly.

  • Dissolved Constituents in Your Fish Tank:

Another potential cause of cloudy aquarium water relates to highly dissolved constituents. If cleaning the substrates does not mitigate the problem, then you should consider this step. The presence of high levels of dissolved constituents such as silicates, phosphates, and other heavy metals can make your aquarium water cloudy.

Solution: Use Testing Kit to check the pH Value

If the water pH value is too high, it means your aquarium is too alkaline. In such cases, a water conditioner can come in handy for treating the water. A water conditioner is not a one-time use, so you should consider investing in a high-quality product.

Another way to solve this issue is by using Reverse Osmosis water.

  • Bacterial Bloom:

Sometimes, the water cloudiness can appear after days, weeks, or even months. If your fish tank experiences this situation, it can be due to bacterial bloom.

Bacterial bloom happens when beneficial bacteria proliferate to consume the ammonia present in your aquarium. The result is cloudy water.

Solution: Eliminate Debris through Vacuuming or Water Change

  • Firstly, do not panic over this issue.
  • Keep your fish tank clean by eliminating debris such as uneaten food or decaying plants.
  • We recommend using a flocculant if you could not remove the debris through vacuuming or water changes.
  • Avoid over-feeding your fish.
  • Over-Feeding Your Fish:

According to Aquarium Fish City, another potential cause of cloudy aquarium water is over-feeding. If you are in the habit of feeding your fish too much, you will constantly experience cloud water frequently. Remember that your fish tank has only a few nitrifying bacteria to break down uneaten food or other wastes.

The reason is the uneaten food will settle down on the substrates. As the food starts to break down, it will produce a significant amount of organic waste, thereby making the water cloudy.

Solution: Avoid Over-feeding the Fish

Many entry-level aquarists think that their fish will starve to death. As such, they end up over-feeding them. This assumption is not true. Generally, fish do not eat every day, and no fish will starve to death a day or two.

Over-feeding can also happen when the whole family members want to participate. As such, it will best if only one person feeds the fish.   

You should always consider feeding your fish at a specific time and provide them the right amount of food.

  • Overstocked Fish Tank:

It is always good to rear different kinds of fish, but overstocking is not the best option. You should note that more fish means more waste in your aquarium. This process can make the water cloudy.

Solution: Reduce Your Stock

The only solution for this issue is to reduce the overstocking of fish. You should always consider the aquarium size when determining your fish population.  Here are some signs that can indicate the overstocking of the aquarium.


To sum up, the above-listed points are potential causes of cloudy aquarium water and are by no means an exhaustive list. However, you should note that algae bloom can also lead to cloudy water. If you want to ensure that algae bloom is not an underlying issue, consider checking this guide to get rid of algae.

About RJ Frometa

Head Honcho, Editor in Chief and writer here on VENTS. I don't like walking on the beach, but I love playing the guitar and geeking out about music. I am also a movie maniac and 6 hours sleeper.

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