One major distinction between aquaponics and typical gardening is the type of grow bed material used.
In typical gardening, soil is used, but in aquaponics, several types of grow bed material can be used.
Understanding and selecting the right grow bed material is an important consideration in planning your aquaponic setup.
There are various considerations to look for when selecting aquaponics grow bed material:
- Neutral pH.
- Safe to touch.
- Not too light, not too heavy.
- Not too expensive.
If you are new to aquaponics, it is important for you to understand what grow bed material is, considerations when choosing grow bed material, and common grow bed materials to work with.
We will delve into those topics below.
What is Aquaponics Grow Bed Material?
As we pointed out briefly, the idea of aquaponics is growing plants in the absence of soil.
Instead, it will be using different natural or synthetic materials to support the crops.
This ensures that the roots are properly anchored, and the seeds can germinate safely inside the materials instead of in the ground.
The grow bed material helps the plants soak in nutrients and prevents them from tipping over during harsh weather in addition to having a place for essential bacteria to grow.
The grow bed material is considered a major piece of the foundation of this type of gardening.
This means that you should give yourself time to familiarize yourself around your options before planning your system.
But just to be aware, not all grow-bed methods of aquaponics require grow bed material.
Things to Consider When Selecting Grow Bed Material
There are countless grow bed material choices available, many people choose non-organic materials, but others prefer to use organic materials.
In light of your preliminary understanding of grow bed material – let’s review some things to consider when selecting one.
pH Neutral
As you go through your aquaponics system maintenance checklist, monitoring the pH level is crucial for your system’s overall health.
When you are selecting your grow bed material, it is essential to remember that certain grow bed materials can impact the pH level and potentially harm your fish and slow your plant growth.
Using pH neutral grow bed materials makes overall pH level management much easier.
Why pH Is So Important?
When managing your aquaponics system, it’s really important to monitor the pH levels. It is so important that checking the pH just once a week is not enough ideally, you would check them every day. The pH should ideally be similar for your fish and plant crops.
It is important to mention that some grow media can shift the pH levels of your aquaponics system. The consequences of these changes are usually slow plant growth, poor health, or even death for fish.
One such grow medium is limestone; limestone will increase the pH very high, well beyond recommended levels.
Instead: It’s a good idea to test your preferred grow media with vinegar before putting it into the system.
Safe to Touch
Because you will be coming in contact with the grow bed material, it’s very important to ensure you do not have any contact with the material that may be harmful to you.
Also, confirm the grow bed material is not only safe to touch but easy to work with, and that you will not injure your hands, etc.
Weight
When looking at the weight of your grow bed material it is especially important if you have a smaller or flimsy setup.
When you select your grow bed material you want to be sure that it can manage weight with the amount it weighs.
In addition, it can put an unnecessary strain on a garden bed if the grow bed material is too heavy.
Because your setup is likely going to be much larger, pick light to medium weight.
Regardless of how you a lot the material, do a good job making sure to evenly spread the material weight across the bed.
Lastly: Depending upon coarse or fine the material is, clogging issues may arise in the water delivery system.
Cost
Cost is definitely something that needs to be considered, and this can be especially true if you are just starting out.
Sure, there are some materials will be cheaper and some materials will be more expensive. Think about your budget and try to stay within that value.
Of course, you also want to think about the fact that some materials you can reuse so even though it may cost more upfront it is going to pay for itself in the long run because you will not be replacing it as frequently.
Yes, you want to be sure to look into your options to try not to spend so much that you do not have money to spend on other things you may want that is important.
For example gravel is cheap because it is prevalent to get in many areas while hydroton is expensive because you won’t find it readily available.
Ease of Handling
You will want to use your hands when placing in the grow medium in your aquaponics garden. The process takes some time, and you want to choose a medium that your hands do not mind.
For example, many growers use lava rock because of its size and porosity compared to other options.
On the downside, the sharp edges on the rock increase the chances of cutting yourself if you are not careful.
The best way to avoid the risk or minimize the risk of dealing with cutting yourself or turning it into a hazard is to simply stick with something that is easy on your hands or wear a gloved to keep in check.
Good Surface Area
As said before, one of the key roles of grow media is to provide surface area for the bacteria to grow.
In general (more surface area = more bacteria) (more bacteria = more quickly the fish waste (ammonia) is converted to nitrates).
Size
Size is also another important factor in selecting a grow media. If the media is too small, then your aquaponic systems will become clogged.
On the other hand, if the media is too large, then the air gaps will slow down your crops growth rates.
The ideal size range is between ½ and ¾ inch. This is enough size and space for beneficial bacteria to establish themselves.
Decomposition
Don’t buy a grow media that will decay during or after the end of a grow cycle.
Decomposition reduces the surface area for the bacteria and interferes with the synthesis of nitrates.
Over time, they can build up and clog your system creating anaerobic conditions that can have a negative impact on the health of your crops and fish.
Grow Bed Material Options
Once you have learned about what to think about when selecting your grow bed material, let’s look at some options now.
And while these options are chosen as the best options, remember, each of them has advantages/disadvantages to consider.
Remember This: No grow bed material is completely ideal.
Coconut Fiber (Coco Coir)
Coconut fiber growth mediums utilize coconut husks in the preparation of the growth medium. This material is also available in both chips and pith.
Coconut fiber’s strength is its soil-like properties. It can filter nutrients in an aquaponics system to ensure plants do not experience either insufficient or excessive amounts of nutrients, which can produce negative results if you are not intentional about either situations.
Coco coir is also pH neutral and has a great oxygen to water capacity, allowing you to grow nearly any crop without concern over acidity or alkalinity.
This medium can also hold water so well that it can be watered without concern for a day or two, in most cases, growers can easily, without concern, water for one day or even two days.
On the negative side, it has poor drainage capacity. The answer to this issue is to simply mix coconut coir with other grow media.
Pros
- Eco-friendly
- Excellent aeration
- Outstanding water retention
- Organic material
Cons
- Poor drainage
- Uncompressed after multiple growing cycles
Lava Rock
When lava rock is formed, it is when hot lava cools rapidly.
If you want your grow bed medium to have multiple surface area features, then this is a definite recommendation.
These rocks have voids that create additional surface area for bacteria that helps plants, in addition to being light, neutral pH, and being able to drain.
That being said, they can be sharp and you risk puncturing your hand or damaging your plant roots.
If you want to use lava rock, you should soak it a few days ahead of time for your plants to be cleaned.
Clay Pebbles
Similar to lava rocks, clay pebbles have an extensive surface area, and they are pH neutral.
While this garden bed medium is only suitable for certain plants, there are many plants on that list.
Clay pebbles contain microscopic holes that enable them to take in enough water while still draining, as well as providing excellent air circulation.
Although clay pebbles are a great alternative for garden bed material, they are not the most cheap option.
One disadvantage to clay pebbles is that they can tend to float on the first introduction. This can affect your system.
Rockwool
Rockwool is produced from a mix of coke, limestone and volcanic rock that is heated until melted. It is then formed into fibers that are made into blocks and slabs.
Rockwool is a great growing media because it is sterile and has good water retention and aeration. It is durable and reusable if you clean it thoroughly and disinfect it after each growing cycle.
The biggest downside to using rockwool is that it is not biodegradable. If it breaks down, you will have to responsibly dispose of the material.
In addition, certain types of rockwool can have an alkaline pH from the bonding agents that make them. You will need to monitor your system regularly if you use rockwool as your growing media.
Finally, it is a very irritating material, it can cause itching of the eyes, skin and lungs. Therefore, you should use appropriate protective gear when working with rockwool.
Lightweight Expanded Clay Aggregates
When clay pebbles are heated under particular conditions, they become lightweight expanded clay aggregates, which are very porous and allow good aeration.
The downside of poor water retention is that clay aggregates keep air flowing freely throughout the grow media without affecting moisture levels.
The downside to this is that your submersible pumps could fail, resulting in wilting plants from drought.
The above reason is to check your system constantly for leaks.
Pros
- High-quality aeration
- High porosity
- Reusable and sustainable
Cons
- Poor water retention
Oasis Cubes
Oasis cubes are made of a form of floral foam that has a sheet-like appearance. As the name suggests, the grow media appears as cubes, holding the air, nutrients, and water to keep your plant(s) alive.
Let it be known that most cultivators use the oasis cubes specifically during the germination stage of the grow cycle and when planting clones from cuttings.
It is not common to see growers use this formulation throughout the grow cycle.
Oasis cubes are pH neutral with good aeration and water retention above average. To the advantage of growers, their open cell structure allows roots to grow freely.
Pros
- Affordability
- Good aeration and water retention
Cons
- Inorganic
- Unsustainable
- Not suited beyond germination and rooting
Sand
Sand is among the most plentiful materials on the planet. It has many useful properties, including versatility, to build and grow etc and most importantly, sand is cheap.
Since sand is made up of so fine a particle it will allow for fair water retention as a grow media. It is perfect when used as a base media during the germination phase.
But it is heavy, has poor aeration, and has to be mixed with other media like perlite or coconut to be more effective.
Pros
- Affordable
Cons
- Bulky
- Poor aeration
- Small particles can block your system
Expanded Shale
Expanded shale acts like lava rock, in that it has air pockets which create additional surface area for bacteria.
Expanded shale is produced by crushing and heating a silicon-based shale.
This material is pH neutral, and its edges are smooth, so are less likely to injure the roots of your plants.
One advantage of this material is that it can be reused, and is generally more budget friendly than alternatives.
For being light and porous, it is still heavier than clay pebbles.
Gravel
Gravel is also inexpensive like sand due to its availability. The difference is that gravel consists of large particles that resemble bits of rocks.
This property will enhance aeration, giving your plants the root oxygen needed for photosynthesis.
The problem with gravel is that it is heavy because it is made of rocks. The vast spaces between the parts of the gravel are also bad for water retention, so your roots will dry out faster.
Pros
- Affordable
Cons
- Bulky
- Poor water retention
Final Thoughts
In recent years aquaponics has grown in popularity for homegrown fresh fruits and vegetables.
A method using material other than soil within the grow bed.
There are so many possible options to select from, it’s hard to know what to choose.
If you’re just starting out you will need to think about the pH level of the material, if it’s safe to touch/work with, the weight of the material, and how much you want to invest.
When selecting a grow media, it should be lightweight, easy to find, pH neutral, and, most importantly, provide great aeration and water retention.
If you’re on the fence on how to choose the best aquaponics grow media, select one of the growth medias above that we recommend.