Algae in Aquaponics and How to Manage it


Algae in Aquaponics and How to Manage it

Algae in Aquaponics and How to Manage it

October 07, 2021

Algae is the number one nuisance for any aquaponics farmer. If left unmanaged, algae can become problematic. Algae can cover the roots of your plants which will restrict them from obtaining the right amounts of nutrients. Algae also causes pH swings and decreases the dissolved oxygen levels in your tank which can become detrimental to your fish and their health. So, let’s talk about algae in aquaponics and how to manage it.

How does algae end up in my Aquaponics system?

First and foremost, algae is a plant. It requires nutrients, air and light to grow. This fast-growing plant disperses their spores that cannot be seen by the naked eye and some airborne spores will inevitably end up in your aquaponics system. And as you know by now, your aquaponic system is deliciously rich in nutrients, providing the perfect environment for algae to thrive.
Algae in water

How can I get rid of algae in my aquaponics system?


Algae require sunlight to grow, so remove light wherever you can! When designing your system, stay clear of any transparent tubing or containers. Go for opaque or black system parts wherever you can. If you have already set up your system with clear tubing and grow bed containers, you can always paint the outside with some black block-out paint.

Your fish are not scared of the dark, so also make sure to cover your fish tank if it is exposed to direct sunlight. This will ensure that the water surface is not exposed to sunlight. Therefore, denying the algae from being exposed to sunlight and preventing algal blooms.

Algae Eaters

By introducing a fish breed that likes to eat algae, you could let nature solve its own problem. However, most algae eaters only eat algae when they are young and will eat plants when they are fully grown. So, this might not be the best long term solution.

Humic Acid

Humic Acid is a chemical that darkens your water. This will block out a fair amount of sunlight, therefore, preventing algae growth in your system. Moreover, humic acid has some nutritional benefits for your plants and fish. Bonus!

Just note that in a shallow DWC humic acid can encourage algae growth and it is best to use this method in deeper water bodies.

Algae eater on algae

How does algae affect my aquaponics system health?

Dissolved Oxygen Decrease

Algae are photosynthetic plants and they use sunlight in the day to create food. However, at night the plant consumes oxygen from its surroundings without giving off any oxygen in return. Therefore, depleting the dissolved oxygen levels in your tank overnight.

If your fish are showing signs of stress or if they’re dying off, make sure to measure the DO levels in the middle of the night or in the early morning before sunrise to see if you could be experiencing an algal bloom.

pH Swings

During the day, algae photosynthesise and consume CO2 from their environment. This gradual drop in COthroughout the day can cause an increase in pH. This is because acid is being removed from the system. But then your pH will drop back down in the evening as the algae will stop producing CO2 and start consuming oxygen. This constant fluctuation in pH will cause stress for your fish and your plants. So it’s best to manage your algae and use methods to either prevent growth or remove algae from your system.


So, there’s a little breakdown about that pesky algae in aquaponics and how to manage it. If you are struggling or you require some assistance please don’t hesitate to book a free 15 min consultation with us to ask us some questions. Otherwise, we wish you the best of luck in keeping the algae blooms at bay.