How to Control Algae

What is Algae?

Algae is a term used to refer to a wide species of photosynthetic aquatic plant organisms without leaves, roots or stems. They can be both microscopic (not visible to the naked eye) and macroscopic. These are present in all aquatic ecosystems, including fish tanks and are necessary to sustain life in water. 

Algae is not dangerous for your fish tank but overgrowth can result in a number of problems. Some algae float in the water while other types can attach themselves to things like aquarium walls, living plants, substrate and other accessories in your aquarium. While they are a wide variety of forms and colors like brown, red, green, blue and black, most that grow in aquariums will be green or brownish. 

Why Does Algae Need to be Controlled?

Algae is necessary to help break down toxic compounds in the water. Some fish also eat algae. Because of what algae does make it important that there is a healthy controlled population of algae in your fish tank. The problem comes when your fish tank has an overgrowth of algae. This is often called an algae bloom. 

Algae blooms can reduce the oxygen levels in the water and can also cause your fish to get sick. Their ability to deplete the water’s oxygen is why we recommend using an air pump if you have regular issues with algae.

Algae can block light that can impact the growth of living plants and fish in your tank. Some types of algae like green algae will make the water in your aquarium look green and murky. This will impact the visibility inside the fish tank, making it difficult to see anything inside of your aquarium with any detail. If you want to enjoy your aquarium, it is important to control the growth of algae to keep it from getting out of control.

Understanding the Causes of High Algae Growth

Before we discuss how to control the algae growth, it’s important to understand what can cause an overpopulation of algae in your tank. Some causes like sunlight are natural while others will depend upon other factors in your aquarium including maintenance. 

Excessive Light Exposure

Exposing your aquarium to direct sunlight for too long can lead to an algae bloom. This is because algae is a plant, and all plants use sunlight for photosynthesis. Algae will absorb sunlight to grow, and without an abundance of light, algae shouldn’t be a problem. 

The artificial light in your aquarium can also create a breeding ground for algae. This can happen if the light is very strong or you keep it switched on for too long during the day. If algae is a problem in your aquarium, light exposure in your tank will need to be monitored. 

Overfeeding Fish

Excessive algae growth can also occur from overfeeding your fish. Algae thrive on nutrients like phosphates, nitrates and other dissolved compounds in the water. These can accumulate in water by excessive fish waste discharge or uneaten food remaining inside your tank. Large dissolved organic compounds levels will lead to excessive algae growth in your aquarium.

Irregular Maintenance

Regular water changes, cleaning the aquarium walls, vacuuming the substrate and other aquarium maintenance tasks are important for every fish tank. Regular cleanings ensure the dissolved organic compounds in the water do not build up too much. Not cleaning your aquarium regularly lets algae promoting chemicals build up and can lead to algae growth. If you have living plants in your aquarium, cleaning the tank will be even more important. Dead or decaying plant matter can result in high levels of dissolved organic compounds in the water. This creates a great environment for algae.

Tap Water

If you are performing water changes with tap water then this could also be a major reason for high algae growth. Tap water can contain high levels of phosphate or nitrate compounds that promote the growth of algae. It’s important to treat tap water before adding it to your aquarium. We will discuss how to treat tap water in the following section.

Different Ways to Control Algae Growth in Your Aquarium

Now that you know what causes the different algae in your aquarium you’ll have a better understanding of how to keep it under control. While it may seem simple, often algae overgrowth or algae blooms can be caused by more than one factor. 

Most of the ways you can control algae are simple and easy to do.

Monitor Light Exposure

If your aquarium has a lot of algae, the very first thing that you should do is monitor the light exposure in your aquarium. Your aquarium should not be exposed to direct sunlight because this can be the main cause of your algae problem. If your aquarium is placed in direct sunlight consider moving it somewhere else. If that is not possible then anything you can do to block the sunlight or minimize the amount of sunlight that reaches your aquarium should help a lot.

Most aquariums will also have artificial lighting and this should also be controlled. If the artificial lighting is too strong, you can often use a dimmer to help control the light’s intensity. Reducing the light’s intensity will help to control algae growth. The lighting should not be on for more than 8 to 10 hours a day. You can do this manually but using a timer helps ensure the light gets switched off on time.

Regular Water Changes

Regular water changes, weekly or every other week will help you keep the algae population in control. You can change between 10 to 25 percent of the water depending upon the type of fish you have. The different types of species and the number of fish will determine the level of water changes you can perform. The water changes will ensure the nutrients levels in the water will not be out of balance. If your aquarium has a lot of fish it will need more frequent water changes.

Changing more than what they can tolerate isn’t recommended even if you have unreasonably high algae levels. This is because changing water in large volumes can remove the beneficial bacteria from your aquarium. Low levels of the beneficial bacteria can give your fish unnecessary stress.

Feed Less Often

For a new aquarium owner it can be fascinating to watch your fish eat all the time. Watching your fish eating can be a delightful and relaxing experience for new aquarium owners, especially for children. Feeding them anytime may seem good but it is very important to feed them only what is needed and not more. They may seem to eat all the food that you give and you may not even realize that they are being overfed. 

Overfeeding them can cause uneaten food to decay in the water or excessive fish waste in your aquarium. Both of these can lead to the accumulation of algal nutrients like ammonia, phosphates and nitrates that can cause an algae bloom. The best way to prevent this is to feed your fish less free.

Check Your Tap Water

Check your tap water to see if it has high levels of nitrates, phosphates and other organic compounds. If you use tap water to perform water changes and it has high levels of these compounds, then it needs to be treated before you do any further water changes. This is very important to control algae growth. You should test the tap water using a water testing kit. 

The tap water can be treated using a Reverse Osmosis (RO) filter. RO filters are effective at removing these compounds and can make your tap water suitable for your aquarium. Filtered water will eliminate most of the unwanted elements that your tap water might have. Commercial phosphate removers or carbon phosphate removers are also effective options to consider. The carbon will help keep the water crystal clear. These come in liquid form and just need to be added to the tap water.

Add Living Plants

Living plants will absorb most of the nutrients and light that algae need to grow. It’s an effective and natural way to prevent algae from becoming a problem. Some plants that float freely or grow up to the top of the tank will limit the amount of light that reaches the lower water levels. Adding living plants does more than just help with algae. Living plants can make your fish tank look more attractive and create natural places to hide for your smaller fish. 

Add Algae Eating Fish

Some species of fish like to feed on algae. These include shrimp, catfish and plecos. Adding a small community of these fish to your aquarium will help prevent an algae overgrowth. A few catfish species like the Dwarf Otocinclus Catfish and Cory Catfish will actively eat the algae in your tank. 

Catfish will also eat excess food that falls to the bottom of your aquarium. This will help prevent a build up of organic compounds in the water. One thing to be aware of is the compatibility of your current fish with the ones that eat algae. Algae eating fish species are small which makes them easy prey for larger and aggressive fish.

Aeration of Water

Adding an air pump or air stone to your tank will increase the dissolved oxygen in the water. The higher oxygen levels promote the growth of beneficial bacteria in your aquarium which is needed to break down organic matter into less toxic compounds. Beneficial bacteria consume fewer nutrients and will directly compete with the algae for nutrients. This will improve your water quality and limit algae growth.

Wipe the Algae Away

One of the easiest ways to remove visible algae from the aquarium walls, and accessories is to wipe them away. This can be done with the help of a sponge or soft brush. The brush can be used to gently wipe the algae from the aquarium walls. Magnetic scrubbers are also available. These are easy to use and let you wipe down your aquarium walls without getting your hands wet.  

To remove the algae from the substrate you can use a siphon vacuum cleaner. This is the easiest way to remove the excessive algae from the substrate. 

Will this Prevent the Future Algae Growth?

It’s important to know that doing the above algae control methods is not a permanent solution to an algae problem. Each way will help you temporarily remove the excessive algae from your aquarium. There is always a chance that you could have algae blooms in the future. This is because no matter how well you maintain your aquarium, a small amount of algae is always present in the water. Future unstable water conditions can lead to algae growth. 

Because there is always a risk of algae blooms, it makes it extremely important to regularly monitor the tank conditions. If you notice excessive algae growing it’s recommended to deal with it immediately to prevent them from getting out of control.