In Aquaponics the plants have a constant supply of water and nutrients. Therefore, growing food in Aquaponics can produce a huge quantity of vegetables. However, some environmental factors have a massive impact on the crop production. Indeed plants need water and nutrients to grow. But they also need light and an appropriate temperature. Growing your food in a greenhouse aquaponics can have many advantages:
A Competition for light
In most gardens there is a natural competition for light between the plants . Plants are growing in height trying to catch the most sunlight possible. Hence, the smaller or younger plants remain in the shade. As a result, the quantity of light available to the plants limit their growth. In a Greenhouse the sun-rays are going through a plastic (poly-carbonate) or glass wall. It spreads the sun-rays in a more diffuse light. Making it more available to all plants height and limiting the competition. Hence, it improves the plants growth and shape. A greenhouse increases the productivity of the whole system. This is a significant advantage of greenhouse aquaponics systems.
How a greenhouse increase the temperature of the system
You have probably heard of the “greenhouse effect”. The sun rays penetrate through the greenhouse. Then, the heat remains in this “closed” environment. This phenomenon allows the greenhouse to keep the air warm. At least warmer than the outdoor temperature.
An improved temperature profile
Temperature is often the limiting factor in aquaponics. Plants and fish metabolism are directly dependent on the temperature of the environment. Hence, when the temperature is low, the growth decrease. On the other hand, when the temperature increase, the growth improves. As a result, the general production of the aquaponics system increase. A Greenhouse is the perfect way to keep the air and the water temperature high. It boosts the production of the system.
Watch out for the big heat!
Yes, the greenhouse effect is an advantage when we want to raise the temperature. But… Be careful as it can also be a threat in summer! If the outdoor temperature is already high, the greenhouse temperature can become unmanageable. Yes, our aim is to keep a warm temperature for our crop. but all species have a maximum temperature after which the growth decrease. If you go far over this limit, the crop simply die…
Classic ways to regulate the greenhouse temperature
Let’s go through the possibilities to keep the greenhouse temperature acceptable:
Doors and windows
The most common practice is to manually open windows and doors. It allows the air to circulate. In warm conditions, the fresh air enters and cool the greenhouse down. Note that this leave opportunity for insects to enter as well.
More elaborated systems have automatic vents. They open when the air reach a specific temperature. Different systems are available. Some are solar, some others are filled with a gas that dilates at specific temperature.
Fans
Fans are also a good option. They can be linked to a sensor. Hence, they turn on when the temperature reach a pre-set limit. Fans can be linked to an external air flow equipped with air filters. In some cases it can help for pest control. Fans also allow to control moisture. They can help to avoid mold in aquaponics.
Boost your greenhouse temperature
Here are some tricks to passively increase the greenhouse temperature:
Chicken coop
You can keep the chicken coop in or next to the greenhouse. Hence, the heat of the animals is kept into the greenhouse. Also, the animals avoid to be exposed to the cold nights of winter.
Passive solar aquaponics greenhouse
Solar systems with heaters allow to warm the greenhouse up and regulate the temperature. And this without receiving the electricity bill at the end of the month. But even more interesting, combining a solar system with the 2 methods detailed below will make your production ecofriendly…
Geothermal system
Soil temperature can also regulate the greenhouse temperature. It allows to keep the temperature cool during the day and warm by night. The principle is very simple. During the day when the temperature gets warm, some of the hot air is blown into pipes buried into the ground. In contact with the ground the pipes will cool down the air. At the end of this pipe, the cool air enters into the greenhouse and cool down the whole culture.
During the night the air temperature decrease. But the same pipe principle warm the cold air and transform it into warm air. Then, release it into the greenhouse. This clever system avoids the large variation of temperature between day and night. It keeps the system very productive at minimal running cost.
Compost heater
Fermentation produce heat and we can use this heat to warm the aquaponics greenhouse. We connect the aquaponics water to a pipe running inside a “compost” in fermentation. It warms the pipe up and increase the temperature of the whole aquaponics system. This is an excellent and ecofriendly way to heat the water. As a result the whole greenhouse warms up. Here is a nice article on compost heated greenhouse
Design of the Aquaponics system into the greenhouse
Height
The greenhouse height is an important point to consider for large climbing plants. If you are limited in terms of height you can bury the sump tank or fish tank into the ground. As a result, you can keep the growbeds close to the ground. Hence, it leaves some height for the plants to develop in height. That said, design your system properly in order to keep your back in good shape. Think of your working / harvesting process and of the of the task ergonomics.
Floor
When it comes to the greenhouse floor you have the option of:
- Keep it as it is (generally earth)
- Add gravels, rocks
- Add pavement or concrete
Earth and gravels allow weeds to grow which is not necessary a problem. On the other hand, concrete surfaces are clean. But algae can also colonize it in high moisture environment. As a result, concrete can become very slippery.
Efficiency, material and lifetime
The efficiency of your greenhouse aquaponics system will be the sum of the different choices and materials you use. Polycarbonate for example is an excellent choice for the panels. It ensure a good insulation and a great light diffusion. Wood is sometimes used for the greenhouse frame. But the lifetime can be limited by the moist environment. Aluminium or galvanized steel are more expensive but last better in time. Geothermal setups are expensive. Indeed, they involve digging and fixing the pipes in concrete. But they pay back in the long term. All those decisions will depend on your specific project and budget. For commercial aquaponics don’t be afraid to invest in lasting materials and technologies.
Example of a backyard greenghouse aquaponics
Now let’s visit Tom who built a hybrid aquaponics system in a backyard greenhouse. It’s a nice example of what can be done on a small backyard. Tom lives in Melbourne Australia. He is opening us the doors to an interesting system. It is composed of both a flood and drain grow-bed aquaponics and a Deep Water Culture (DWC) aquaponics.
Fish tanks
The fish tanks are in-ground Intermediate Bulk Containers (IBC) covered by a deck. You actually don’t see the tanks when you enter in the greenhouse as they are literally under your feet. Tom is currently growing Australian native fish such as eel tail catfish, and Murray cod. He also plans to add trouts into the system.
Fish feeding
Tom lift the deck / tanks lead to have access to the fish. The setup is very neat and tidy.
Water flow
A water pump raises the fish tanks water to 2 different growing setups:
Flood and drain grow-bed
The flood and drain grow-bed section contains 2 grow-beds. A bell siphon is present in each grow-bed. Tom choose to work with clay balls as media. Those 2 Grow-beds are produce very well. A large sweet potato plant is currently transforming the greenhouse into a jungle.
Deep Water Culture
The Deep Water Culture section contains 2 raft tanks equipped with air stones. Polystyrene rafts are floating on the surface. They support pots where plants are growing.
With the DWC, Tom announce better results on leafy vegetables. While the Grow-bed technique is giving excellent fruit crop.
We thank Tom for his time and congratulations again for the very nice system. Tom thought each square meter of this greenhouse to allow a nice food production.
You will also find more information on greenhouse gardening from those websites:
If you are inspired by Tom’s greenhouse, you will probably be interested to discover my six steps to build and manage an Aquaponics system. Click here to access for free! Thanks and good reading 🙂
