Aeration in Aquaponics

Aeration bubbles in the fish tank of an aquaponics system

Aeration in Aquaponics

Aeration in Aquaponics

October 07, 2021

Something that we need to remember as Aquaponic Farmers is that our set-up is a living, breathing ecosystem that requires adequate levels of oxygen available at all times. Fish and plants require oxygen to survive and today we will walk you through our aeration system setup to help both you and your system breathe a little easier.

Fish Tank Aeration in Aquaponics

As any aquaculturist would tell you, fish are finicky. Without the correct level of dissolved oxygen, you will have fish gasping for air at the top of the tank. And unfortunately, some dead fish within the hour! If your fish densities increase so does the oxygen consumption so make sure you do your calculations!

Pump Size (L/min) = Tank Volume (m3) x Required Oxygen (ppm) x 2 x # of tanks

We like to use x2 Jebao Air pumps connected in parallel as a fail-safe backup. We recommend using a diaphragm compressor pump as they are low on power and high in pressure. The size of the air pump is dependent on your type of fish and their oxygen requirements.

The pumps are then connected to a Metala Air Diffuser Ring or a diffuser disc that runs along the inside of the tank as they offer the least backpressure while diffusing oxygen into the water.

Bubbles in a fish tank in an Aquaponics system

Airlift Aeration in Aquaponics

Another method that we like to use is the airlift. This is a simple design that can be used in addition to the Metala Air Diffuser rings to aerate and circulate the water. The basic idea behind an airlift is to inject air into the bottom of a submerged waterpipe. Therefore, allowing the bubbles to rise to the top. The water inside the pipe will be more buoyant as it is aerated. Which creates an upward displacement of the water.

Note: It’s often more efficient if the height that the water has to be lifted (h1)  is small in comparison to the height of submergence (hs).

Take a look at the diagram below extracted from OPTIMIZATION OF A BACKYARD AQUAPONIC FOOD PRODUCTION SYSTEM KEITH CONNOLLY & TATJANA TREBIC for a better understanding.

Figure 32: Conceptual diagram of an air lift pump (Dela-Cruz, 1982) Extracted from: OPTIMIZATION OF A BACKYARD AQUAPONIC FOOD PRODUCTION SYSTEM BY KEITH CONNOLLY & TATJANA TREBIC

Grow bed Aeration in Aquaponics

Plants require oxygen to be provided at root level for optimal growth and survival. The minimum amount of oxygen required is usually 2ppm (3-4l/minute air pump per 1000lt od DWC)

The good news is, if you have a flood and drain, nutrient film technique, dutch bucket or a wicking bed setup then there’s no need to worry about aeration. This is because the plants will receive natural oxygen from their environment. Just make sure that you are using the correct grow media that won’t suffocate your plant roots and allow for air pockets in the grow bed.

But let’s say you have a deep water culture setup.  You will definitely need some aeration systems in place to ensure your plants are getting their required 2ppm. We like to use our trusty Metala Air Diffuser tubing again by connecting it to run across the length and width of the DWC. Air stones are also a possibility here as long as there are no stagnant corners in your DWC. A bonus to aerating your DWC is that improves the water circulation in the bath.

Algae Phenomena

When you are measuring your levels of dissolved oxygen it is important to understand that you will have fluctuations due to algae. A high DO in the day and a lower DO at night is expected if you have an algae problem.

Here at Ichthys, we like to say that a well-aerated system is a happy system so make sure you plan out our aeration designs accurately.  Check out our online store to find all aeration components mentioned above and get your aeration system up and bubbling!