How To Get Rid Of Green Aquarium Water [5 Best Ways]

Keeping your aquarium clean and ensuring your underwater pets are healthy and happy is incredibly important. Yet, a common problem that often troubles aquarium enthusiasts is the presence of green water. 

This article aims to present you with an uncomplicated and user-friendly manual to get rid of green aquarium water and stop it from returning. 

I’ll delve into the various types of algae responsible for this problem, the reasons behind it, successful remedies, ways to prevent it, and whether it could harm your fish. 

So, let’s begin our journey.

Types of Algae in Fish Tanks

In the water, just like the plants you see on land, there are these tiny, plant-like things called algae. When too many of these algae gather in your fish tank, they can make the water look green and cloudy. 

Now, there are different kinds of these algae that can make this happen. Let’s talk about three main types:

  • Green Algae: Just like its name, this algae is green in color. It’s the most common type and can cover surfaces in your tank, like glass or rocks. It’s a bit like the moss you might see on the ground outside.
  • Blue-Green Algae: This type is a bit different. It’s not really green; it can be greenish-blue or even brown. It tends to form slimy layers on things in your tank, and sometimes even floats on the water’s surface. It’s a bit like the slippery stuff you might find in a pond.
  • Diatoms: These are tiny golden-brown spots that can appear on surfaces like glass and decorations. They look like dust or sand, and they often show up when a tank is new or hasn’t been set up for a while. It’s a bit like finding a sprinkle of cinnamon in your tank.

Each of these algae types behaves in its own way and grows under certain conditions. Think of them like different kinds of plants in a garden – they have their own colors and shapes, and they like other things to help them grow. 

Understanding these algae types can help you figure out how to keep them under control and make sure your fish tank stays clear and healthy.

What Are The Causes of Green Aquarium Water?

The reason behind green aquarium water is a bit like when too many plants grow in one place. In this case, it’s because a certain type of very small green algae, known as “planktonic algae,” starts growing a lot. 

These tiny algae creatures reproduce rapidly when there’s a lot of food for them, like too much light, giving the fish too much food, and water that hasn’t been cleaned well. 

When these things come together, the algae get really happy and start to make the water turn green. It’s kind of like how plants grow when they get lots of sunshine, water, and nutrients from the soil.

What Does It Look Like?

When the water in your aquarium becomes green, it might seem like you’re looking through glass that has a bit of color on it, like when you put on sunglasses. Or, it’s as if you’re peering through a soft mist, similar to what you might see on a foggy morning. 

This greenish haze occurs because there are a huge number of super tiny algae bits floating around in the water. These little algae particles are hanging in the water and making it look this way. 

It’s a bit like how dust or tiny particles can make the air look less clear, except in this case, it’s happening in the water of your aquarium.

Methods To Get Rid Of Green Aquarium Water

green aquarium
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1. Reduce Light Exposure

Algae really like light, so if you control how much light your aquarium gets, it can make a big difference. 

Try to keep the light on for about 8 hours each day. It’s like giving the algae a little less of what they love, so they don’t grow too much.

2. Feed Fish Wisely

Remember, just like we shouldn’t eat too much, fish shouldn’t have too much food either. When we give them more food than they can eat fast, it can make the water in the tank messy.

So, when you feed your fish, give them only what they can eat quickly – in a few minutes. This ensures that no extra food hangs around to make the water messy.

By doing this, you’re not only keeping the water clean and nice for the fish, but you’re also making sure they get the right amount of tasty food without any problems.

3. Water Changes

Think of your aquarium as a little underwater world. Just like we need fresh air, your fish need clean water. 

By changing some of the water regularly, you’re helping to remove the stuff that algae use to grow. It’s like giving your fish a nice, clean home.

4. Use of Algae Treatment

Sometimes, you can use special stuff called treatments to fix the green water. It’s a bit like using soap to wash your hands. These treatments are made for aquariums and they work to remove the extra algae. 

Remember, it’s important to read and follow the instructions carefully, just like you would when using a new shampoo. This way, you’re helping your fish tank become clearer and healthier.

5. Add Aquarium Plants

Bringing in some live plants to your aquarium is like having more neighbors in a neighborhood. 

These plants compete with the algae for food, making it a bit harder for the algae to grow a lot. It’s like sharing snacks so that no one gets too many.

By trying out these different ways, you’re working to create a balanced and healthy environment in your aquarium. It’s like finding the right balance between eating your favorite foods and staying active to feel good.

What Fish Eats Green Water?

Just like some of us have favorite foods, there are certain fish that really enjoy eating algae. Algae are like a snack for them. These fish include Siamese algae eaters, Chinese algae eaters, and plecos.

When you bring these fish into your aquarium, they can help you with the algae problem. They gobble up the algae, kind of like how we eat our favorite treats. It’s like having little helpers who tidy up the place by munching on the algae.

So, having these fish in your aquarium can be a smart choice if you want to keep the algae from growing too much. They happily eat it up, making the water clearer and more pleasant for both the fish and you.

What Are Some Practical Ways to Prevent Green Water In Your Aquarium?

1. Proper Filtration

A good filtration system is like a special tool that works to remove the yucky things in the water, like fish waste and extra food that algae really enjoy. 

Investing in a good filtration system is like getting a top-notch cleaning team for your fish tank. It helps make sure that the water stays fresh and clear by getting rid of the things that could make the algae grow. 

It’s like having a reliable friend who’s always there to help keep things clean, making your aquarium a cozy and pleasant home for your fish.

2. Regular Maintenance

In your aquarium, there might be things like leftover food, pieces of plants, or other stuff that shouldn’t be there. 

You need to take them out, so the water stays clean. Also, if you have plants in your aquarium, sometimes their leaves might get old and turn brown. 

You should trim those brown leaves off. It’s like giving your plants a little haircut so they can stay healthy.

3. Controlled Light

An aquarium is like Goldilocks looking for the perfect porridge – not too hot, not too cold. Just like that, your aquarium needs the right amount of light – not too much, not too little. 

If it gets too much light, it’s like the water is throwing a party for tiny green things called algae. Algae can turn the water green, and that’s bad for your fish and other aquatic friends.

So, it’s important to find the right balance between not too bright and not too dim. Think of it as giving your aquarium just the right amount of sunshine to keep it happy and the water clear.

Is Green Water Potentially Harmful?

The green water you see in the aquarium is not directly bad for the fish. It’s kind of like having a green-colored decoration in the water. However, when there’s way too much algae growing, it can start causing some issues.

Algae, as they grow a lot, might use up more oxygen in the water. Imagine if lots of people were breathing in a small room – the air could become a bit thin. Similarly, if the algae grow too much, they can use up too much oxygen, which fish need to breathe.

Also, the presence of too much algae can signal that there’s something else not quite right with the water. It’s like a sign that says, “Hey, something might be off here!” This could mean there are other problems with the water quality that could be harmful to the fish.

So, while green water itself isn’t too bad, letting the algae go wild could lead to less oxygen for the fish and hint at bigger problems. It’s like keeping an eye on things to make sure your fish stay happy and healthy.


Overcoming the challenge of green aquarium water might feel overwhelming, but armed with the right information and steps, you can confidently overcome this problem. 

Learning about the different kinds of algae, what triggers their growth, and the techniques to remove and stop them will enable you to establish a livelier and healthier underwater world for your beloved fishy friends. 

I appreciate your time and attention in reading this.


Are algae bad for fish?

Not all algae are bad for fish. Some fish actually like to eat certain types of algae, and a little bit of algae in the tank can be okay.

But if there’s too much algae, it might make the water less clear, and this could be a problem. So, a little algae is fine, but too much can be not so good.

What is a home remedy for green algae?

A simple thing you can try at home to help with green algae is to reduce the amount of light your aquarium gets. Algae like light, so giving them less of it can slow down their growth.

Also, you can make sure not to overfeed your fish and change some of the water regularly. These things can help control the algae. But if the problem gets really big, there are special treatments you can find at pet stores that might help. Just remember to follow the instructions carefully when using them.

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