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What Causes Green Algae in An Aquarium

The experience of unpleasantly green water is ubiquitous for any aquarium keeper. This green water is due to the excessive growth of algae in your fish tank. Algae is a common name for a large group of photosynthetic eukaryotic organisms. Algae use light, water, and nutrients to maintain their lives.

Green algae are commonly present in freshwater aquariums. Their presence is significant because some aquarium pets like snails, and some fish use algae as food.

But the problem becomes more complex when the algae grow exponentially and blur the aquarium view. In severe cases, you can't even see the fish. Therefore, it is necessary to control the algae growth.

Here are a few reasons and solutions for exponential algae growth, which will help you in your fish tank maintenance.


Causes of an algae outbreak

Algae is just like the other aqua plants. Like the other plants, it also requires three main ingredients for proper growth: Water, light, and nutrients. The recipe will be spoiled if there is an excess of any ingredient among these three. The imbalance will raise the growth of algae like a wildfire or outbreak of weeds in the garden.

The aquarium behaves slightly differently from your lawn, where you can control all of these three necessities to take over the weed.

Aquarium offers complete control over only two main things: light and nutrients. Excess water is inevitable, but you can handle the aquarium water to a certain extent. In the following, a few common reasons for the exponential growth of algae in any aquarium are listed.

  • Too long in water changing
  • Overfeeding aquarium pets
  • The aquarium is exposed to sunlight directly
  • Lights are on for a more extended period
  • Imbalance in the nutrient environment in the aquarium


How to get rid of excessive algae growth

To know the true reason for algae growth is winning the half battle. Once you know the true reason for algae growth, the next step is effortless. You have to take only preventive measures to control that reason. Here are the methods of  managing  the exponential growth of algae.


1. Control the lighting hours

Light is an essential factor for sustainable life in aquariums. It helps the plants in the photosynthesis process. But the excessive light is the main cause of the algae outbreak.

It is recommended to turn on the light between 8 to 12 hours to control the algae outbreak. Set that lighting hour at which algae color turns brown to green. It would be best if you had to set it properly because either a short or long period will cause excessive algae growth.

Never expose your tank to direct sunlight for the whole day and even partial hours of a day. This exposure will explode the growth of algae, and it won't be easy to control such growth of algae.

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2. Control feeding

Excess of everything is bad, and it is severe in case of aquarium’s ingredient balance. The majority of the aquarium holders overfeed their aquarium pets. Then the excess feed decomposes and converts into phosphate. The phosphate will give rise to the algae growth in your aquarium.

Therefore, it is necessary to provide a balanced quantity of food to your aquarium pets. For balance, there is a litmus test to supply the food that pets consume within 5  minutes. It will help to control the algae growth.


3. Water change

It is the most important single factor that can only significantly impact your aquarium atmosphere. You have to change the water of your aquarium every week. Otherwise, there will be nitrate accumulation.

Nitrate is an essential nutrient for plant growth. If it accumulates, then it gives rise to the algae’s growth. Therefore the change is 10 to 15 % water weekly.

Besides the other nutrients, it will also help to keep the nitrate level low in your aquarium and help to control the excessive population of algae.

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4. Water test

Water is inevitable for aquarium pets and creatures like plants and shrubs. Therefore, knowledge about the source of water. If the source contains a high quantity of nutrients like nitrates and phosphate, they will cause excessive algae growth. Test your water source to avoid danger.

If you find excessive nutrients in the aquarium, treat them with chemicals as certain chemicals help balance the nutrients. If it looks costly, then change the source of water.

Before selecting a source, perform the test as well with that source. You also can use the filtered water in your aquarium for a crystal clear view.

Hygger 8-in-1 Aquarium Test Strips

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5. Cleaning of Aquarium

Clean up the aquarium regularly. Clean your aquarium when you see the algae engulfing the glass, rocks, and other hard surfaces of the aquarium. Use the algae cleaner to remove the algae by scraping the glass. Remove the stones and scrub them. When you change the water, then vacuum the gravel as well.

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6. Grow aqua plants

Growing aqua plants are much helpful in fighting against excessive algae growth. However, many aquarium keepers don’t like them because they require regular maintenance.

But these plants are beneficial because they use excess nutrients present in the water and reduce the nutrient level. When there is less fuel, it will be very difficult for algae to grow appropriately.

Aquarium plant

7. Maintain a balance between nutrients and light

Keep a balance between aquarium light and nutrients. Whenever there is an imbalance between these two factors, the algae will grow rapidly.

Algae is a less complicated plant type. It can easily consume the light for photosynthesis and nutrients for growth compared to the other aqua plants.

When there is less light and nutrients, it will use them efficiently compared to other plants. Then algae will suppress the growth of the other aqua plants and fade your aquarium view.

So, now more about your aqua plants and pets. Supply them according to desire. There are several algae-eating fish available. These fish help to suppress the algae growth. Siamese flying fox, Plecostomus, nerite snails, Otocinclus, and many others are included.



It is not possible to make your aquarium algae-free. But it is possible to control excessive algae growth. To have proper control keep an eye on the water source, and never feed your fish excessively.

Besides, these raise natural algae cleaner in your aquarium, such as nerite snails, Siamese flying fox, Plecostomus, Otocinclus, and many others. These species will limit the algae growth in your aquarium besides the enhanced aesthetic beauty.

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