How To Get Rid Of Algae In Koi Pond Naturally

How To Get Rid of Algae in Your Pond and Fish Tank

If you own a pond or a fish tank, chances are you’ve faced the issue of algae growth. Algae can be a nuisance and make your pond or fish tank look unsightly. Luckily, there are several ways to get rid of algae naturally without harming your aquatic pets.

Why Does Algae Grow in Ponds and Fish Tanks?

To understand how to get rid of algae, it’s essential to know why it grows in the first place. Algae thrive in water that has high levels of nutrients, particularly nitrogen and phosphorous. These nutrients can come from various sources, such as fish waste, leftover fish food, and decaying plant matter.

Additionally, algae require sunlight to grow. So if your pond or fish tank is located in an area that gets direct sunlight, algae growth is bound to happen.

1. Keep the Water Clean

The first and most crucial step in getting rid of algae is to keep the water clean. This means regularly removing any debris, dead leaves, and uneaten fish food from the water. A pond skimmer can help do this job quickly and efficiently.

Also, make sure to clean your filters regularly as they can accumulate organic matter and become a breeding ground for algae. A clean filter ensures that the water remains clear, which makes it difficult for algae to grow.

2. Reduce Nutrient Levels

As mentioned earlier, high nutrient levels in water promote the growth of algae. To reduce these nutrient levels, it’s essential to limit the number of fish in your pond or fish tank. Fish produce waste, which is a significant source of nutrients for algae.

Additionally, avoid overfeeding your fish as leftover food can release excess nutrients into the water. If you have plants in your pond, make sure to trim them regularly and remove any dead or decaying matter. This step reduces the amount of organic matter in the water, thus lowering nutrient levels.

3. Use Natural Algae Removers

Many natural remedies can help keep your pond or fish tank free of algae. One of them is using barley straw. Barley straw contains compounds that inhibit algae growth. You can use barley straw by placing a bale in your pond or placing a mesh bag filled with straw pellets in your fish tank.

Another natural remedy is adding plants that can absorb excess nutrients. Plants such as water lilies, water hyacinths, and duckweed can help reduce nutrient levels and shade the water, preventing sunlight from reaching the algae.

3.1. How to Use Barley Straw to Get Rid of Algae

To use barley straw, first, you need to find the right amount for your pond or fish tank. The general recommendation is to use one pound of barley straw per 1000 gallons of water.

You can place the barley straw bale directly into the water or use a mesh bag to hold the pellets. Place the bag or bale in a spot with good water movement, which allows the water to flow freely through and around the straw. The straw should last for about six months and needs replacement once it decomposes.

3.2. How to Use Plants to Get Rid of Algae

Using plants to control algae growth is simple. The first step is to determine which plants are suitable for your pond or fish tank. Once you’ve identified them, plant them in containers and place them in the water.

The plants will absorb excess nutrients from the water, which in turn reduces algae growth. Additionally, the plants provide shade, which inhibits algae growth as they require sunlight to thrive.

4. Use Beneficial Bacteria

Beneficial bacteria can help keep your pond or fish tank clear of algae. These bacteria break down organic waste, such as fish waste, leftover food, and decaying plant matter, into nutrients that plants can absorb. This reduces the nutrient levels in the water, thereby preventing algae growth.

Additionally, beneficial bacteria can compete with algae for nutrients, further reducing their growth. You can obtain beneficial bacteria from specialized stores or online retailers. Follow the instructions on the package to use the bacteria correctly.

5. Use a UV Clarifier

A UV clarifier is a device that uses ultraviolet light to kill algae and other microorganisms in the water while leaving beneficial bacteria unharmed. The clarifier works by drawing water through a chamber that contains a UV lamp. The lamp emits UV-C rays, which destroy the algae’s cellular structure, preventing it from reproducing.

A UV clarifier is an effective way to get rid of algae, but it can be expensive. Additionally, it only kills algae and not the underlying cause of the problem, which is high nutrient levels in the water.

6. Use Chemicals as a Last Resort

If all else fails, you can use chemicals to get rid of algae. However, this should be a last resort as many chemicals are harmful to aquatic life and the environment.

If you decide to use chemicals, read and follow the label directions carefully. Additionally, make sure to test the water before and after using the chemicals to ensure that they don’t harm your fish or plants.

Frequently Asked Questions (FAQ)

1. Can Algae Kill Fish?

Algae itself is not harmful to fish. However, if the algae growth is excessive and covers the entire pond or fish tank, it can reduce oxygen levels in the water, which can harm your fish. Additionally, some types of algae can produce toxins that can be harmful to fish.

2. How Often Should I Clean My Pond or Fish Tank?

You should clean your pond or fish tank regularly to prevent the buildup of organic matter that contributes to algae growth. The frequency of cleaning depends on the size of your pond or fish tank, the number of fish, and the amount of debris that accumulates. A general rule of thumb is to clean your pond or fish tank every two weeks.

3. Can I Use Bleach to Clean My Pond or Fish Tank?

No, you should never use bleach to clean your pond or fish tank. Bleach can kill your fish and harm the plants in your pond or fish tank. Additionally, bleach can leave harmful residues that can be difficult to remove, even with several rinses of water.

4. Can I Use Salt to Get Rid of Algae?

Salt is an effective way to kill algae, but it is harmful to some types of fish, such as koi and goldfish. Additionally, salt can accumulate in the water, making it unsuitable for aquatic plants. If you want to use salt to get rid of algae, make sure to use the right amount and only for a short period.


Algae growth is a common problem faced by pond and fish tank owners. Luckily, several natural and safe ways can help control and prevent algae growth. Keeping the water clean, reducing nutrient levels, using natural remedies like barley straw and plants, and introducing beneficial bacteria are all effective ways to remove algae naturally. However, if all else fails, you can resort to chemicals, but make sure to use them as a last resort and with caution.

Ways to Get Rid of Algae Effectiveness Cost
Keep the water clean Effective Low-cost
Reducing nutrient levels Effective Low-cost
Using natural remedies Effective Low-cost
Introducing beneficial bacteria Effective Low/Moderate cost
Using a UV clarifier Highly effective High cost
Using chemicals Effective High cost