The grow bed is one of the main components of an aquaponics system, along with the fish tank and the water transfer system. It is the foundation of the aquaponics system and the place where plants are grown and nurtured.
The grow bed is also the largest component of an aquaponics system, so if you are planning to set up an aquaponics system, you must make the right choice in choosing the right grow bed for your aquaponics system.
The three main types of aquaponics systems that are often used in aquaponics are:
- The raft system of aquaponics or Deep Water Culture (DWC) that used floating rafts to grow plants.
- The nutrient film techniques (NFT) that use holed PVC pipes with net pots to grow plants.
- The media-based Method or Flood and Drain that uses grow media to support plants.
In order to have proper planning on what type ofgrow bed you want to use in your system, it is important to know the pros and cons of different aquaponics systems.
However, in this article, we will focus on the grow bed that is used in a media-based aquaponics system. The grow bed in a media-based aquaponics system holds three main functions:
- It housed the important beneficial bacteria that convert fish wastes into plant food.
- The grow bed contains the grow media that supports plants up and provides structures for the roots to hold on.
- It helps filter solid wastes in the water and traps it in the bottom of the grow bed.
Important things to consider in choosing the right aquaponics grow bed
- Choose a grow bed that is made of food-safe and non-toxic materials.
- The grow bed must be strong and thick enough to hold the weight of your grow media, plants, and the force of constant draining and filling of water.
- Avoid using metals because metals can corrode quickly and can cause imbalance to your system.
- Choose a waterproof, grow bed.
- Choose a grow bed that is deep enough to hold different varieties of plants and vegetables.
Grow Bed Size and Depth
Your grow bed should be able to provide enough filtration for the nutrient-rich water in your system. The plants are part of the filtration process in your system, so you must have enough surface growing area in your system. The length and width of your grow bed should provide enough surface area for the plants, and together with the depth, it should be able to give enough volume.
Most aquaponics experts suggest that the ideal grow bed in media-based aquaponics system should have about 12” of media depth, with the top 1-2” left dry to reduce algae and fungi growth. However, some experts suggested that you can also grow successfully in much less depth of 4-6”. These different suggestions can create confusion for any aquaponics beginner, but this is just a suggestion or guideline. So how deep should your grow bed be?
In answering the question, one thing we need to think is, the deeper the grow bed, the more costly it will be. It will be expensive to fill your grow beds with grow media if you have a larger system, but if you use a shallow grow bed, there are also limitations on what plants you can grow.
Short – lived plants like lettuces and greens can grow in shallow grow beds. But when it comes to deeply rooted plants like cucumbers and tomatoes, shallow beds can’t provide the base for them to grow and also spaces for their larger root zones.
There is no right or wrong to grow bed depth choices. It will depend on what you see your system needs and what plants you’re planning to grow. If you’re planning to grow only short-lived plants, you can go for shallow beds, but if you’re planning to grow deeply rooted plants then, you need to choose a grow bed with more depth
The Three Aquaponics Grow Bed Zones
Grow beds in the media-based aquaponics system have three grow bed zones, and each zone has different purposes and functions. It’s a good idea the learn what is the use of each zone as it will help you determine what is the right grow bed size and depth for your system.
- Zone 1 – The Surface or Dry Zone
The surface or Dry Zone is located on the first 2” of the grow bed. This area minimizes evaporation and protects the plant base against collar rot. Keeping this area dry will also prevent algae growth on the surface area of the grow bed media and moisture-related diseases such as powdery mildew.
- Zone 2 – The Root Zone
The root zone is the next 6” – 8” area. These are where root growth and plant activities happen. During the drain part in the flood and drain cycle, the water will completely drain away, allowing for the efficient delivery of oxygen-rich air to the roots, beneficial bacteria, microbes, and composting worms (if present in the system).
The incoming water during the flood part of the cycle helps spread moisture, nutrients, and incoming solid fish wastes throughout the area. Where the composting worms will help break down solid matters and turning it into nutrients for the plants’ roots to absorb.
- Zone 3 – The Solid Collection and Mineralization Zone
This zone is located at the bottom 2” of the grow bed. This zone is where fish wastes and worm castings are collected. What is left of the solids during the flood and drain cycle are in this zone where further and final mineralization occurs with the help of beneficial bacterial and earthworm.
Aquaponics Grow Bed Ideas
You can purchase a ready to use grow bed or make your DIY grow bed in aquaponics. Here are some commonly used aquaponics grow beds to give you ideas in choosing the right grow bed for your aquaponics system.
1. IBC Grow Bed
One of the most common aquaponics grow beds is the IBC totes. This grow bed is mostly used by DIY aquaponics gardeners in media-based or flood and drain aquaponics system. The IBC totes are recycled and used as grow beds and fish tanks.
IBC totes are ideal grow beds in aquaponics as they are durable and can be modified easily to suit your specific needs. Because IBC Totes are mostly used IBC, the most important thing to keep in mind in using IBC totes as grow beds is to know what was in IBC totes you are buying. Fish are sensitive creatures, and chemicals that used to contain some IBC totes might affect the health of your fish and plants. Use only IBC totes that are previously used for food products.
2. 55 Gallons Barrel Grow bed
Another popular to DIY aquaponics gardeners, are the 55 gallons barrels that are recycled into grow beds. Barrels are readily available and economical. All you have to do is cut the barrel in half lengthwise, and you’ll have your grow bed. However, make sure that the barrels are cleaned entirely before using it as your grow bed. Some barrels used to contain chemicals that can poison your new aquaponics system.
3. Old Bath Tubs
Old bathtubs have been recycled into grow beds by several backyard aquaponics gardeners. Using old bathtubs will allow you to grow a more extensive aquaponics system. However, just like any other grow bed, make sure that the bathtub is cleaned and chemical-free.
4. Wood Framed Grow Bed with Pond liner
Wood-framed grow beds lined with pond liners are also used by some DIY backyard aquaponics gardeners. It is made of a simple wood frame that has a wooden floor and a plastic pond liner to ensure that the water stays where it should be. The great thing with a wooden grow bed is you can make a specific size that fits your aquaponics system’s needs. Just make sure to varnish or paint your wood to protect it from termites.
5. Aquaponics Grow Bed Containers
If you have no time for DIY grow beds, you can use ready-to-use aquaponics grow bed containers that are readily available. It might cost you a little, but these grow beds are thick, durable, food-safe, and made specifically for aquaponic gardening.
As one of the main components of your aquaponics system, you must make the right choice in what grow bed to use in your system. There are many aquaponics grow beds that you can use in your system, but what you think is the best suitable one will depend on the type and size of the aquaponics system you have.
Whether you decide to a DIY grow bed or purchase one, what matters is you are using a food-safe, durable, and appropriately sized grow bed for your system.
Keep in mind that your grow bed’s function is to hold your grow media, provide enough space for filtration, and provide enough planting area for your plants to grow. Make your decision based on these three main grow bed functions, and you will never go wrong. Thank you for reading our blog. Join our Facebook Group for more aquaponics updates and learnings.