Aquaponics 101: Growing Plants and Fish Together
- HDT Team
- 12 minutes ago
- 3 min read
At Happy Dancing Turtle’s Northern Lakes location, growing produce happens almost year-round, thanks in part to the Atrium growing area which is home to an aquaponics system. Here are some basics of how the aquaponics system works.
Diving into Aquaponics
Aquaponics is a form of hydroponics, which uses fish and their fish waste as the fertilizer for plants. It is a natural-based system relying on biology/microbes to convert solids and organic matter provided by the fish into usable nutrients for the plants. In these types of systems it can take a few weeks before the microbes start to get established, as the biology increases the system gets better over time.
With traditional hydroponic systems, plants are usually grown without a substrate (or base layer), and their nutrients are provided with a water solution using man-made fertilizers. These types of systems do not need the biology to convert the fertilizers into a usable form for plant growth. The drawbacks of these types of systems are higher cost, more labor intensity, high water consumption, and the buildup of salts which need to be removed periodically.
In the middle of the aquaponics layout is the tank where the fish live with grow beds on either side. The pink grow lights ensure there are enough light hours during winter months to match the summer growing season . At the far left, the white tank is part of the water return system. The white stand pipe at far left of the photo is an experimental pre-filter to trap large particulates for mineralization.
This view of the left side of the system shows fava beans, cilantro, parsley, leaf lettuce, arugula, cabbage, bachelor button flowers, dill and garlic.
This view of the right side of the system shows fava beans, nasturtium flowers, parsley, kale, mint, cabbage, bachelor button flowers, and kohlrabi.
Goldfish and sunfish, currently 35 in total, make up the fish population of the system. The goal is to have one pound of fish per 5-8 gallons of water. Overcrowding may lead to fish stress.
The fish are fed up to 3 times per day with high protein ominous fish food. The food does not contain copper sulfate which would kill the beneficial microbes. Their diet is supplemented with leafy greens and composting worms which are grown within the system.
Media Beds
Media beds, located on either side of the fish tank, are where the plants grow. The media beds also trap the fish waste and solids. This is the main filtration of the system, and is where the plants grow. The media is known as L.E.C.A it stands for Lightweight, Expanded, Clay, Aggregate. This clay is heated in a kiln where it expands like popcorn, it is very lightweight and P.H. neutral. The clay is very porous, it has tiny holes and air pockets. These open spaces create lots of surface area, this is where the microbes live. When planting, seeds go directly into the media.
This view of the media beds shows loose leaf lettuce seedlings. The pink color is due to grow lights. Plants use mostly blue light during their growth phase and light in the red spectrum during their flowering and fruiting phases.
Role of Microbes
The microbes provide nutrients to the plants by eating the fish waste and solids that are trapped in the media, when they consume these solids they break them down to a microscopic size as they pass through their gut by pulling off molecules and making these nutrients available and small enough for plant roots to “take up” otherwise these nutrients would not be in a usable form for the plants. This is the stomach of the system. Along with the microbes, there are springtails and earthworms that add to the cleanup crew and biology of the system. They help to further break down solids for the microbes.
Flood & Drain System
This type of system is called a Flood and Drain, also known as Ebb and Flow. This is a closed loop system that recirculates the water, making water consumption very low. It runs on12 volt pumps that flood the media beds with nutrient-rich water then drains back into the tank, As the water drains back it pulls oxygen down into the root zone, trapping the solids as the water passes through the L.E.C.A. which returns clean, filtered water back to the tank. This cycle repeats about every 12-15 minutes. A bell siphon is used to activate the drain cycle, following Bernoulli’s principle. Watch for a future blog exploring the workings of the bell siphon.
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