If you are getting worried seeing your fish tank water turn green, you’ve come to the RIGHT place. I’ll be sharing with you some tips on combating common algae problems in aquaponics systems.

algaeRSAlgae are common and natural in aquaponics system. In a balanced aquaponics system that is running smoothly, the algae population should be stabilized.

When existing as a stable population, such as a very thin slime on the water surface or at the sides and bottom of the tank, algae is actually beneficial to the system as it is part of the ecology.

They could be sheltering some beneficial bacterial species and serve as a natural source of food for some fish species.

Moreover, algae produce oxygen in the day, helping to raise the dissolved oxygen water content of the water in the fish tank.

Problems arise when the population of algae goes out of control. This often happens when the system is in the process of getting cycled.

First, Let’s Understand What are the Dangers and Problems Caused by Algae Bloom.

In the day, algae carry out photosynthesis, producing oxygen while consuming carbon dioxide and nutrients from the fish waste. However in the dark, photosynthesis stops and the algae consume oxygen instead.

Hence, when there is an algae bloom in the fish tank, the dissolved oxygen and nutrient content of water in the fish tanks are depleted, thereby starving the aerobic organism in the aquaponics system (fish, aerobic bacteria and plants) of dissolved oxygen as well as depleting the nutrients needed by the plants.

To make matters worse, when algae accumulate and die off, decomposition takes place. Decomposition is a process that consumes huge amounts of oxygen.

The changes in carbon dioxide levels (carbon dioxide is a weak acid) in the water during day and night as a result of photosynthesis by algae, can also cause swings in the pH levels.

Wild swings in pH levels can be very stressful to the health and well-being of the fish.

How Do We Then Combat The Common Algae Problems?

As mentioned earlier, not all algae growths are bad.

If you are just seeing a thin biofilm (very thin layer of green slime) at the sides and bottom of your fish think, there’s no need to worry or make any attempt to remove them.

TIP: The simplest way to reduce algae is by shading because algae need sunlight to produce food, grow and reproduce. The fish tank should be located in a shaded area and a cover should be placed at the top of the fish tank to block off as much sunlight as possible. Moreover, a darker and cooler environment is preferred by the fish.

If the water in the fish tank looks green and it’s very hard to see through it, this means that suspended algae are present in your system. This is a natural part of the cycling process. It is almost always due to excessive nutrients and sunlight entering the fish tanks.

You will need to cover the top of your tank to block off as much sunlight as possible, pump full to aerate the system, bump up and clean your filters.

And very importantly, stop feeding the fish as all the nutrients will be going to the algae promoting further algae bloom.

If you are seeing filamentous algae in the tanks, you will need to be more concerned. The long strands of algae can potentially get the fish tangled and colonize the entire fish tank. You should cover the tank to block off all sunlight and remove the long strands of algae manually. You might also want to add some known algae eaters into the tank to clean it up.

If there are algae on the grow bed, it is undesirable. You will need to check that the top layer of the grow bed media, which is exposed to the sunlight, is not wet. The overflow drain where water from the fish tank enters the grow bed should be at least 1 inch below the surface.

To combat the algae growth, pile more grow media above your current grow bed. You might also want to add some composting worms to the grow bed to consume the algae and uneaten dead organic matters.

What’s Next?

To sum it up, algae seldom cause huge problems in aquaponics system over the long-run once the system is cycled and stabilized. Most of the algae problems arise at the start when the system is getting cycled.

The best way to control and combat algae issues is through shading of sunlight and filtration, combined with a little more patience. The media-based grow bed functions as a bio-filter.

While it is not compulsory to have an external filtration system if you are using the flood and drain aquaponics design with the right stocking ratio, many people are incorporating it to better remove unwanted solids from the water before flowing into the grow beds.

Filters (or clarifier) are often expensive to buy, but you can also make a simple DIY pre-filter very cheaply.

Find Out More…

What I suggest you do now is to check out John Fay’s Aquaponics 4 You for detailed aquaponics design guidelines and step-by-step videos to guide you through the construction and cycling of your own DIY aquaponics systems.
You will even receive bonus e-books that teaches you how to grow your own worms for the media-based grow bed!

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Combating Algae Problems in Aquaponics System was last modified: February 28th, 2017 by Gab