Algae, Blog, Maintenance

Why Did My Aquarium Water Turn Green?

Water turn green, image of aquarium with green water

So, why did your water turn green…??

You love your aquarium, and, like me, you stare it all day everyday. Until one day, when you wake up and see that your aquarium water has turned green. What happened?! Why did your water turn green and what you should do next? In this article, I will explain why aquarium water turns green, how you can prevent it, and what steps you can take to clear the green water in your tank. Whether you are new to fishkeeping or have been in the hobby for years, this guide will give you some insight on how to maintain a clean and healthy aquarium.

Table of Contents

What Causes Green Aquarium Water?

Green aquarium water is most often a result of a bad algae outbreak, or algae bloom. Algae are tiny plant-like organisms that grow in water with excess nutrients, light, or both. When the right conditions are met, algae can grow rapidly, turning the water green. The most common type of algae that causes green water is called “green water algae” or “pea soup algae.”

There are a few factors that can contribute to algae growth in your tank:

1. Excess Light

This is by far the most common cause for green water. Algae love light. If your aquarium receives too much direct sunlight, this may be a problem that needs attention. Or, if you leave the tank lights on for extended or excess periods of time, you create the ideal environment for algae to flourish. Make sure your aquarium is not placed near a window where it receives direct sunlight. It’s ok for indirect light though, you just don’t want the sun beaming directly on it.

2. Nutrient Imbalance

Algae feed on nutrients like nitrates and phosphates. These nutrients can come from excess fish waste (doodoo), uneaten food, and decaying plants. If your tank has high levels of nitrates or phosphates, it can lead to major algae growth. If you test the water regularly, that can help you monitor these levels and make necessary adjustments, like water changes or chemical additions.

3. Poor Water Circulation

Stagnant water can also encourage algae growth. Good water circulation helps distribute nutrients and oxygen evenly throughout the tank, reducing the chances of algae getting a foothold. Ensure your aquarium filter is working efficiently and clear of debris to promote proper circulation.

How to Prevent Green Water in Aquariums?

Preventing green water from ever forming is easier than dealing with an algae bloom that has already formed. Here are some tips to keep your aquarium water clear and green free:

1. Control Lighting

Limit the amount of light your aquarium receives on any given day. Use a timer to ensure the lights are on for 6-8 hours a day, which is usually adequate for most aquatic plants, assuming the light is decent. If your tank is near a window, consider moving it to a location where it gets less natural light during the day. Or, considering getting a light with a built in timer or 24/7 cycle. These type of lights span several light cycles, from orange, in the morning, clear white in the day, and blue at night. This give you the ability to see inside your tank more often, but less overall light that may cause algae.

2. Maintain Water Quality

Second to light is nutrients. And the best way to control the level of nitrates in your water (besides a good feeding routine) is water changes. These are crucial for maintaining good water quality. Aim for a 20-30% water changes every week. This helps remove excess nutrients that can fuel algae growth and cause a problem that could get out of control. Use a reliable water test kit to monitor nitrate and phosphate levels regularly.

3. Add Live Plants

Live plants help compete with algae for nutrients. By adding plants like Anubias, Java Fern, or Hornwort, or floating plants like Dwarf Water Lettuce or Frogbit you can naturally reduce the nutrients available for algae to feed on. Plants not only help prevent algae but also enhance the overall appearance and water quality of your aquarium.

4. Use a UV Sterilizer

If all else fails, get a UV sterilizer. These can kill algae spores that are floating in the water, preventing them from turning your tank green. This tool is especially useful for tanks that are prone to algae problems. Consider investing in a UV sterilizer on Amazon for effective algae control.

These prevention methods can help you avoid green water issues altogether. For more tips on maintaining a healthy aquarium, check out our article on best aquarium maintenance practices.

How to Clear Green Aquarium Water?

If you’ve missed your chance for prevention, and your aquarium water has already turned green, don’t worry. There are several ways to clear it up:

1. Perform a Large Water Change

Start by performing a very large water change, we’re talking 50%. This will help remove a significant amount of algae, but also remove excess nutrients that are fueling the algae. However, avoid changing more than 50% at once. Doing so can stress your fish, or cause a cycle crash — which is another problem entirely.

2. Use Algae Control Products

There are various algae control products available that can help eliminate green water. These products contain chemicals that kill algae. Follow the manufacturer’s instructions carefully to avoid harming your fish or plants. Here’s a recommended algae control product on Amazon or consider adding a little Seachem Flourish Excel. Just remember, these products should be used sparingly, and temporarily. We always want to address the cause of the issue, not just treat the symptoms. But, these will help you if your tank is far beyond help.

3. Increase Filtration

By upgrading or adding additional filtration, you can help clear out the green water. A high-quality filter with activated carbon can remove dissolved organics that can contribute to algae growth. Consider investing in an efficient canister filter with activated carbon for better water clarity. Each carbon pouch should last about a month, so one pack will get your three months down the road, and hopefully, out of the woods.

4. Reduce Feeding

This tip can help reduce a whole slew of problems, beside just algae. But reducing the amount of food, or the frequency of feeding, can vastly reduce the amount of nutrients in the water. This will help fight algae growth. Reduce the amount of food you give your fish and remove any uneaten food when possible. This one strategy can be the most effective in helping lower nutrient levels and reduce algae.

By following these steps, you can restore clarity to your aquarium and rid yourself of the green water. Remember, consistency is key to preventing future algae issues from cropping up.

Conclusion

Green aquarium water can be very frustrating, I get it, but understanding what causes it and solutions to stop it, can make managing it much easier. By controlling light, maintaining water quality, and using the right tools, you can prevent green water and enjoy a crystal-clear aquarium. Regular maintenance and vigilance are the keys to keeping your tank in top condition.

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