How to Fix Cloudy Tank Water

Regardless whether you are a novice aquarium hobbyist or you have been cultivating fish tanks for a decade or longer, you are probably going to experience a problem with cloudy tank water at one time or another. In most cases, cloudy tank water does not pose a significant threat to your fish but it can affect the appearance of your tank and it may point to additional problems such as poor water quality.

If you are currently dealing with cloudy water in your tank you should first determine the cause of the situation before you can move on to finding the solution. The key to solving any problem with your aquarium is to take the time to understand the problem first so you can make an informed decision in regard to treatment. In this article you will learn the basics about what causes cloudy tank water, how to treat it, and how to prevent it from happening again.

Causes of Cloudy Tank Water

The most common cause of cloudy water in the freshwater aquarium is a bacterial bloom. Similar to an algae bloom, bacterial blooms occur when there is a sudden increase in the number of bacteria present in the tank – high concentrations of bacteria in tank water often result in a cloudy or milky appearance of the water. Bacterial blooms are very common in tanks that have just been set up but have not been properly cycled. The nitrogen cycle is the process through which beneficial bacteria in your tank work to break down wastes, converting toxic substances like ammonia and nitrite into less harmful nitrates. These bacteria thrive in tanks where there is a significant accumulation of organic waste and in tanks where the ammonia and nitrite levels are very high. If your tank hasn’t been properly cycled, or if it has a significant amount of organic debris built up in the substrate, you might experience a bacterial bloom.

Another possible cause for cloudy tank water, as mentioned, is an algae bloom. Algae blooms typically result in green tank water so if the cloudy water in your tank does not have a green tint, it is most likely a bacterial bloom. Algae blooms are likely to occur when the tank is exposed to high levels of light or carbon dioxide and when there is an excess of nutrients in the tank. If your aquarium is positioned in direct sunlight or if you leave your tank lights on for more than 12 hours a day, the conditions could be right for a sudden increase in algae growth – an algae bloom. Excess nutrients resulting from waste build-up in the substrate and high levels of carbon dioxide in the tank may also lead to an algae bloom.

A third possibility regarding the cause of cloudy tank water is dirty substrate. If you are setting up your tank for the first time you need to thoroughly rinse your sand or gravel substrate before you put it in the tank to get rid of dust and dirt. When preparing your substrate for use, place it in a large plastic bowl or bucket and run cool water over it. Use your hand to agitate the substrate as the water is running, letting the excess drain over the sides of the bowl. When the water in the container runs clear (meaning there is no dust or dirt left), your substrate is clean and ready to use.

Treatment Options

If you are experiencing cloudy tank water for the first time you may be tempted to simply buy a commercial water clarifier off the shelf – if you do, you should not be surprised if the treatment doesn’t work or, if it does, that the condition recurs a few days later. These treatments may help improve the clarity of your tank water but they will not solve the problem that caused the condition in the first place. You need to be very careful when using chemical water treatment solutions because you never know what kind of side effects they might cause. Changing the chemistry of your tank water is delicate business – most fish do not respond well to sudden changes in tank water so, while a water purifier might resolve the cloudiness of your tank water for a little while, it could case changes in water chemistry that might harm your fish.

In order to completely solve a problem with cloudy tank water (the correct way) you need to improve the water quality in your tank and remove the built-up waste from the substrate. Start by siphoning the gravel in your tank using an aquarium gravel vacuum and perform a 25% water change using tap water that has been treated with an aquarium water conditioner. By siphoning tank water from the substrate you will be collecting and removing accumulated detritus that might be contributing to poor water quality in your tank. It will also serve to remove the organic material on which bacteria and algae may be feeding. When you perform a large water change, the cloudiness of the tank water may not go away immediately but, as the water quality in your tank goes up, the bacteria should eventually settle down. Keep an eye on your tank over the next few hours to see if the cloudiness starts to go away – if it doesn’t, wait 24 hours then perform another water change. When you refill the tank, make sure you treat the new water with a water conditioner to remove chlorine and heavy metals that could be harmful for your fish.

Preventing Cloudy Tank Water

To prevent a recurrence of cloudy tank water you must take a few key steps to keep the water quality in your tank high and to keep the level of accumulated waste low. Avoid overfeeding your fish because any uneaten fish food will simply sink to the bottom of the tank and break down as waste, providing bacteria and algae with essential nutrients. You should also be sure to keep up with your routine weekly water changes – change between 10% and 20% of your tank volume on a weekly basis and be sure to siphon some of the aquarium substrate during each water change. Replacing your filter media on a monthly basis will help ensure that your filter is functioning properly, removing dissolved wastes as well as solid waste from your tank water.

If you take these steps you should have no trouble keeping the water quality in your tank high. The cleaner your tank is, the less likely you are to have trouble with cloudy tank water.