How To Clear Green Aquarium Water [05 Definite Ways]

Have you looked at your aquarium and noticed it has green water? Don’t worry, you’re not the only one! Nearly every aquarist has had to deal with this issue. 

Green aquarium water is frustrating, and it implies that you don’t take care of your aquarium correctly. However, you’re a responsible man, and you tried your best to have a crystal clear aquarium. But unfortunately, that didn’t pay off. 

So, why does water turns green, and how to get rid of the green color in aquarium water. For a variety of causes, phytoplankton, a kind of algae, surges in abundance, turning the water green.

The good news is that repairing the green water isn’t too time-consuming. You can rapidly get rid of green aquarium water with the right adjustments and tools.

Stay tuned! This article will show you how to clear green aquarium water using five easy steps! So, don’t wait any longer – let’s get started!

Why Does Water Turn Green?

An algal bloom is to blame for your aquarium’s recent breakout of green water. Phytoplankton is suspended in the water in millions or billions of microscopic fragments. Phytoplankton is a member of the Chlorophyta division, which includes between 9000 and 12000 species of green algae.

You can’t see phytoplankton with the naked eye; you need a microscope to observe them. But the only thing you can perceive is their combined presence, which is nothing but green water.

Phytoplankton under a microscope

As opposed to other types of algae, green algae grows in the water rather than on the surface. When the population is low, the water in your aquarium will take on a greenish hue. What’s frightening is how quickly it multiplies by billions, and the green haze becomes thicker and thicker until it’s impossible to see through.

Everything in your aquarium might be ruined if you don’t do something about it. The color of this water may change from a bright green to a yellowish-green depending on the environment. However, it’s still the same green algae.

Yellowish Green Aquarium Water

One of the most common green algae species in aquariums is the green dust kind. However, aquarium water does not become green due to the presence of green dust algae. Instead, until disturbed, green dust algae adhere to the surfaces. In fact, the water in your aquarium may seem green due to light reflections.

In contrast, the algae (phytoplankton) that are the source of the green water are free to float wherever in the water.

Make sure you have phytoplankton and not green dust algae before taking any action. Take a sample of your aquarium’s water, for example. Cloudy green water indicates the presence of phytoplankton without a doubt. However, if the water is clean, it’s green dust algae.

Green Dust Algae Vs Phytoplankton Green Water

Let’s go on to learn how to swiftly and simply remove green water from an aquarium. 

Therefore, before taking any steps, make sure you are affected by phytoplankton, not green dust algae. For example, take a water sample from your aquarium. If it’s cloudy green water, it’s definitely phytoplankton. On the other hand, if the water is clear, it’s green dust algae. 

Now, let’s go forward to know how to clear green aquarium water easily and quickly. 

Is Green Water Bad For Fish And Plants?

Even though green water seems unappealing, it isn’t detrimental to fish or other aquatic animals. In their native home, many fish thrive in green water.

The phytoplankton also has a positive effect. Some aquarists raise or buy these to feed their reef aquarium’s corals. Phytoplankton is cultivated (also known as infusoria) by certain breeders to supplement the diets of their microscopic fish fry.

Is Green Water Bad For Fish And Plants

Aside from looking bad, green water may also interfere with plant development if it completely obscures the light. Getting rid of green aquarium water is thus an absolute need. Let’s find out first what are the causes of green aquarium or phytoplankton bloom. 

#01: Excess light or Direct Sunlight:  

The photosynthetic pigment in green algae is the same percentage as in plants, making them seem like plants. Light is used by algae to grow.

Algae blooms are more likely in aquariums that are kept in direct sunlight. One of the fundamentals of fishkeeping is to keep the aquarium out of direct sunlight. It is well known that direct exposure to sunlight not only promotes the development of algae but may also increase the temperature of a fish tank.

Excess light or Direct Sunlight
Excess light or Direct Sunlight Causes Green Aquarium water

An excess or greater intensity of artificial light may also lead to the development of algae. Healthy plants and fish in aquariums don’t need light for more than 8 to 12 hours a day, at most.

The easiest technique to get rid of green aquarium water is to reduce the amount of time the lights are on. I propose shutting off the lights at night to avoid disrupting the fish’s circadian cycle and discouraging the development of algae in the tank.

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A built-in timer would be preferable to continue turning on and off the light manually. You may also purchase a separate timer and connect it to your aquarium’s lighting system.

#02: Nutrient imbalance

Algae and plants both require nutrients to thrive. Nutrients like nitrates and phosphates, which algae need, are found in fish food and waste, as well as in your tap water.

Algae growth may be exacerbated by overfeeding, overcrowding, or a lack of filter capacity. Additionally, doing water changes with water that is high in nutrients might promote the growth of algae and color your aquarium water green.

too much or imbalance in nutrients causes green aquarium water
Too much or imbalance in nutrients causes green aquarium water

Planted tanks also need frequent fertilizer dosing for optimal plant development. A nutritional imbalance, on the other hand, might throw your aquarium into disarray.

After the requirements of plants have been addressed, excess nutrients will be utilized to satisfy the needs of algae. Since excessive usage of fertilizers might foster the formation of algae, you must take care.

As a result, it’s important to routinely monitor water parameters and address any issues that arise.

#03: Neglecting to Maintain Your Equipment: 

Water quality deteriorates with time as a result of poor upkeep and a shortage of water. Nitrates and phosphates rise as a result. Consequently, it fosters the growth of algae in an optimum habitat.

You don’t realize how awful the circumstances are until something goes wrong since you can’t see the nutrients. As a result, whether you like it or not, regular aquarium cleaning is essential for their health. In reality, many aquarium-related issues, such as algae and disease outbreaks, may be avoided simply by performing regular maintenance on the tank.

Poor Maintenance can lead to green aquarium water

The following items should be on your to-do list:

I’ve written a supplementary post on how to prevent common errors made by newcomers, which you’re welcome to read.

How To Clear Green Aquarium Water 

Despite the fact that prevention is always the best option. You’ll need the correct tools to battle and remove green aquarium water if you must deal with it.

To get rid of green water, I tried four different things and these are the ones that worked best for me. Don’t be discouraged if you’ve already tried something else and it didn’t work out. It is hoped that the following solutions will be of great use to you.

How to Clear green aquarium water

#1: UV Sterilizer

UV Sterilizer

Installing a UV Sterilizer in your aquarium is the fastest and easiest solution to get rid of green aquarium water. Algae floating in the water, as well as numerous disease-causing organisms, will be destroyed as it passes through the UV chamber. In only a few days, you’ll be able to enjoy a clean and healthy aquarium!

More read:  Best UV sterilizer for the fish tank (Choose from my top picks)

So, UV sterilizers are the solution to your green water issues. They’re absolutely safe for fish, invertebrates, and plants. Moreover, they’ve grown increasingly inexpensive in recent years- so it’s time you give one a try!

There are several UV sterilizers on the market. You may select one for your tank. If you ask me which one I suggest, I’ll pick Coralife Turbo-Twist UV Sterilizers. It is available in three sizes, suited for aquariums up to 500 gallons, economical and dependable.

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#2: Water Polishing Pad

Water Polishing Pad

Because phytoplankton is so little, your aquarium’s filter will be unable to catch it. Adding a water polishing pad to the media chamber of your aquarium filter may convert it into green water cleaning machine. 

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If you use a polishing pad, you may remove the smallest particles from the water of your aquarium. The outcome is water that is pristine and transparent. 

Install it as the filter’s last mechanical filter medium and replace it when it becomes clogged. 

#03: Dhapnia 


Do you prefer a natural solution to your aquarium’s green water? DEFINITELY, Daphnia would be a great selection in your case.

Phytoplankton is a favorite food for Dhapnia, and you can get it online or at your local pet shop. It doesn’t take long for a hundred Daphnia to clean the murkiest green water.

Treating your fish with Dhapnia is an excellent idea. Betta and tetra fish, among others, will delight in the Daphnia feast.

However, it is essential that you accurately identify phytoplankton as the source of the green water. That’s because other algae don’t get eaten by Daphnia.

#04 Diatom Filter

The use of Diatom Aquarium Filters is an excellent technique to maintain a clean and healthy aquarium environment. Diatomaceous earth (Diatom) is used in these filters to remove impurities from the water and to polish or eliminate algae that have developed.

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Some aquarium filters have the ability to charge diatoms, which gives unparalleled water cleaning. One of them is the Marineland Magnum Polishing filter. You may learn more about how diatoms can improve the polishing power of a filter by watching the video below.

#05: Chemical Treatment

Many items on the market now promise to remove green water from the water. One of them is API AlgaeFix, which is used to eliminate algae that cause Green Water outbreaks.

However, most do not address the root source of the issue, and their outcomes cannot be assured.

As a result, using chemicals should be the last choice. You don’t know how the chemical will interact with the aquarium’s fish, invertebrates, or plants.

Make sure you read the label and directions thoroughly if you have to use this product. Keep in mind that overdosing might make your condition worse.

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That’s all you need to know about how to clean green aquarium water. All of the solutions stated above are successful, but I’d love to know if you have any further ideas or recommendations on how to get rid of green aquarium water.

I hope you found this post useful and instructive. Please use the comment box below if you have any queries or remarks. Thank you for your time!

Sujit Modak

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