Tips to Pond Algae Control Safe For Fish

Tips to Pond Algae Control Safe For Fish

Excessive algae growth can be a disaster for your pond. It creates a toxic environment that can kill aquatic life, isn’t safe to swim in and results in discolored, unsightly pond water. Algae that continues to grow out of control can quickly transform your pond from a gorgeous garden pond into an embarrassing eyesore. These tips will help you get your algae under control without harming your aquatic life. 


Algaecide for ponds is a chemical that is poured into backyard ponds. This chemical creates a reaction in the water, such as oxidation, that helps kill algae and prevent future growth. Most brands of algaecide work in a matter of days. 

Some brands of algaecide are safe for use with fish, but others are not. Because of this, it is important to read the labels of products carefully before purchasing them. Popular brands of algaecide that are safe for fish include: 

- GreenClean Algaecide

- Cutrine Plus Algaecide

- API Pond Algaefix Algae Control

These brands offer products that are EPA certified and are considered safe for the aquatic life in your pond. 

When using an algaecide product, it's important to make sure that you maintain appropriate oxygen levels in the water because they are known to cause oxygen depletion. Using an aerator while you are treating the pond is recommended to keep your pond plants and fish safe. 

Treating your pond in sections is equally important because it helps pond owners avoid overtreating their pond, which can kill fish and plants. Start at one end of your pond, and treat one section every two days. 

After using algaecide, you will need to manually remove the dead algae because it produces toxins in the water that can make the water unsafe. Dead algae will typically float to the bottom of the pond. Use a muck shovel to remove it. 

Algaecide can have a negative impact on beneficial pond bacteria. Because of that, it's important to add good bacteria to your pond when using an algaecide. If you don't, there will not be enough beneficial bacteria in the water to prevent algae growth in the future. 

Algaecide is not ideal for a mini pond due to the high concentration of chemicals. These products are best suited for a larger pond. 

UV Pond Clarifiers

UV clarifiers are a natural treatment that is used to kill algae. They do not affect the oxygen content of the water or the water quality. 

When algae are blasted with strong UV lighting, the cells die, preventing algae from growing. Powerful UV lighting can kill algae at every stage of the growth cycle. It can help prevent the abundant growth of toxic algae long before it starts. 

UV clarifiers are installed on your pond filter so that the water passes through the UV light as it is filtered, killing blue and green algae. It's important to note that this method of algae control is only effective for blue and green algae. 

When using one of these, it's important to remember to clean your filter regularly. Large pieces of dead algae can get stuck in your filter, clogging it. This will result in an unhealthy pond environment and your filter needing to be replaced. 

Remove Algae Manually

Algae that are floating on top of your pond water can be removed with a rake or muck shovel. This method is not going to be effective at removing all of the algae in a pond, though. It's important to manually remove algae in combination with other methods. 

Manually removing algae will not work well for all types of pond algae. It is best used for floating algae and string algae. 

Pond Plants

Pond plants can help prevent and control algae growth over time. These are not going to work as quickly as water treatments, but they can be effective on a long term basis. 

Plants require the same nutrients and oxygen content that every type of algae does. As your amazing pond plants grow, they tend to instantly absorb excess nutrients that are in the water. This means that algae trying to grow will not have the excess nutrients that they need in order to survive. 

Invest in plenty of new plants that will grow quickly to naturally combat algae growth. These plants will absorb excess nutrients faster than small aquatic plants, helping to naturally combat algae faster. 

Floating plants that block out sunlight can also help prevent algae growth. Green water algae require a certain amount of sunlight to grow, just as plants do. Both too much and too little sunlight will kill green water algae. Because floating plants, such as Water Lillies, prevent sunlight from reaching algae they make it more difficult for algae to grow. 

Algae Eating Fish

Investing in fish that eat algae is a wonderful way to make sure that all kinds of algae cannot grow in your pond. Popular fish that eat algae include: 

- Koi fish

- Water snails

- Goldfish

When using fish to control algae in a pond, it's important to remember that this solution will take time. Fish only eat when they are hungry, and they only eat a small portion of algae at a time. If you have an overgrowth of algae in your pond, it's best to take care of the large amounts of algae first. Then, put algae eating fish in your pond to help prevent excessive algae growth in the future. 

If you use fish to combat algae, it's important to keep an eye on how much algae is in your pond. When algae eaters run out of algae to eat, they will begin to eat aquatic plants. Some fish will attack others when they are hungry, too. Having too many fish and not enough algae will upset your ecosystem in the long run. 

Research fish before buying them to make sure that any fish purchased are compatible with your pond.

Pond Dyes

Algae cells need sunlight in order to grow, just as other plants do. This applies to all types of algae, but green water algae are more sensitive to a lack of sunlight than other types of algae are. 

When you use pond dyes, the colored water helps prevent sunlight from reaching algae cells. This inhibits its growth. 

When using pond dye, it's important to research products carefully. Some pond dyes contain harsh chemicals that are not suitable for aquatic life. 

Beneficial Bacteria

The beneficial bacteria in a pond helps naturally combat the bad bacteria, making it a wonderful way to prevent algae in ponds. It does this by using the same nutrients that algae need to grow, starving the algae before they can begin the growth cycle. 

Using beneficial pond bacteria is not a quick fix. It will reduce algae in ponds over the course of several months. This method is best used to prevent algae growth instead of to combat a large algae problem. 

Beneficial pond bacteria should be added to every new pond to prevent algae in ponds. This is because new ponds typically contain filtered water. When water is filtered, it removes both the good and bad bacteria in the water. 

However, if there is one algae cell that does not get filtered out, it will result in algae growth. Adding beneficial bacteria immediately after installing your backyard pond is the best method of preventative pond algae control. 

Feed Fish Less Food To Control Algae Growth

When pond owners overfeed their fish, it results in excessive nutrients in pond water. Algae hungrily eat these nutrients to grow at an alarming rate. In order to prevent algae, you need to make sure that there are not enough nutrients in the water for the algae to thrive. 

As a general rule of thumb, you should not see any extra fish food in the water after feeding your fish. If you do, you are overfeeding them. 

Feeding your fish less can also encourage them to eat algae. Make sure that the breed of fish you have in your pond will consume vegetation. Then, feed them half of the amount that you normally would. They will then eat the algae in your pond for food. 

Double Check The Water Quality

Algae grow at an alarming rate in ponds that have poor water quality. This is often caused by high pH levels in the water. First, check your pond chemistry for high pH levels. They sell pH water testing kits at most pets stores and online marketplaces.

You simply put a few drops of your pond water into a vial, and then check the color of the water in the vial with the color sheet that comes with the kit. The color sheet will tell you what the color of your water means. 

If your pond chemistry is off balance, it's important to determine the cause. Overstocking fish will give you a higher pH level in a matter of days. It's important to slowly add more fish to your pond to avoid upsetting the pH balance.

Fertilizers that are running into the pond water are common culprits. This is frequently seen in larger farm ponds. Keep an eye on anything that might be running into your pond water to help determine what you need to do in order to create a healthy pond environment. 

If you have introduced anything new into your pond, such as new decorative rocks, that may be why your pH balance is off. Double check everything in your pond to ensure that it is not made from limestone or granite, both of which will upset the pH balance in your pond. 

Cool Down Your Pond Water

First, make sure that your pond fish can handle cooler temperatures. Most fish that are not tropical fish can, but it is always better to err on the side of caution. 

Then, start lowering the temperature of your pond water. Toxic blue and green algae thrive in warmer water. Once the temperature starts to drop, algae will have a harder time growing. 

A large shade that extends over your pond is a great way to keep the water cool. When using this method, keep the needs of your aquatic life in mind. Pond fish can survive with minimal sunlight, but plants will die. This is not a great solution for larger ponds, though. 

A small jet just below the surface of your pond will help keep the water cooler. Water becomes hotter when it is still, which is why the constant motion that a jet provides will help lower your water temperature. 

Floating plants can keep water cool to help prevent algae growth. These provide shade just like an awning over your pond does, but they do not provide so much shade that your plants will die.

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