Aquaponics Grow Bed Depth – What You Need to Know

Aquaponics Grow Bed Depth

The grow bed represents a container that allows plants to grow in an aquaponics system. Such beds come in different sizes, depending on the size of your system. The design must be sturdy and support the weight of all the plants as they grow up. But then, what about the grow bed depth? How deep should it be for your system to thrive?

The depth is affected by numerous myths and controversies. What works for some systems will not work for every system. For example, most growers sharing their experiences online recommend around 12 inches of it. The top surface – one or two inches – will be left dry. The primary goal is to prevent fungi from growing there. Then, you will also find people who claim on spectacular results with less than that.

As a general rule of thumb, a deeper bed will cost a bit more than normally. After all, you need to pay more for the extra media as well. Then, there is another cost involved with supporting the weight, not to mention the larger tank to deal with all the media. Besides, if you use a lower depth – such as up to six inches, you can rely on drain trays instead.

Now, while in theory you might be able to reduce the grow bed depth, the truth is you do not want to do that. How come? Limitations will naturally kick in as well. Of course, if you have a low budget, you might be limited to certain sizes. But then, being aware of the limitations can help you make more informed decisions.

Types of plants you will grow

A shallow grow bed will work wonders for short living plants, such as spinach, lettuce or other green plants. Generally speaking, it is suitable for short living plants. The same type of design will fail on longer living plants – those with deep roots, such as corn, cucumbers or tomatoes. Watermelon is also out of discussion.

The reason? A shallow bed will not offer a solid base of nutrients. Plus, the bacteria will be limited as well. Therefore, long lasting plants will not be able to survive. Think about the space they require as well. On another hand, an impressive grow bed depth will give you limitless possibilities. Going down to 12 inches in depth will let you handle most types of plants with no issues whatsoever.

spinach with roots
spinach with roots

Considering dead zones and maintenance

Dead zones may inevitably occur in a deeper aquaponics grow bed. These areas are anaerobic and bring no benefit to the environment – in fact, they may actually reduce its effectiveness. If the bed is deep enough, you will have plenty of beneficial bacteria or worms, as well as space for the roots to grow. Maintenance becomes a piece of cake then, as all these organisms will do the cleaning for you. The point is to come up with a self-sustaining system and providing enough space is the key – aim for a grow bed depth of about 12 inches.

The system will naturally be split in a few zones. The surface is about a couple of inches and it is relatively dry, preventing plants from developing collar rot.

The second zone is where roots thrive. It requires about seven inches. It is responsible for bringing oxygen to the plant roots, as well as soil microbes and positive bacteria.

Finally, the third zone covers the last few inches of the grow bed. This is where waste solids and castings are collected. By this time, solids have been reduced by more than 50%. Any leftovers get to this area.

As you can see, each of these areas has its own role. There are certain processes occurring throughout each zone and they all work together in a tight collaboration to promote the self-sustaining profile of the environment. Failing to provide adequate space for each zone will inevitably reduce the activity. If one of these areas fails to deliver, all of them will be affected and the whole system will inevitably die.

It is worth noting that you might be able to find a balance without a very deep grow bed. It takes some trial and error to figure it out, but it is totally doable.

Final words

With these thoughts in mind, most people would rather pay attention to anything else related to the aquaponics system than the grow bed depth. This aspect is often overlooked in the process, yet it plays a massive role. In fact, it represents one of the first things to pay attention to in the planning. Planning involves considering every aspect related to your aquaponics system, from the actual fish and plants to the design of the bed and the depth. Consider the amount of water required for your plants and fish, as well as the bacterias to create a self-sustaining place.

Suggested articles:
Aquaponic Grow Beds – Everything You Need To Know
Aquaponics for Beginners – Everything You Need to Know Upfront
How To Determine The Ideal Fish To Plant Ratio For Aquaponics?
Aquaponics Fish Food Explained – What Options Do You Have?
Desktop Aquaponics Explained – Is It a Good Option?
What Is Aquaponics? – Everything You Need To Know Upfront
How to build an Aquaponics System?


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