Your choice of grow media will significantly impact the cost of building and maintaining your aquaponics system. But with so many types of grow media available, it is confusing to know what will work best for you. That is why we wrote this guide to help you understand what aquaponics grow media is, what are the available choices and what will work best for you.
What is Aquaponics Grow Media?
Aquaponics grow media is a natural or synthetic soilless material that supports the body of your plants. Like soil, it protects and ensures that plant roots are established in the correct position.
The grow media also serves as a surface area for bacteria to thrive inside the grow bed and acts as a filter for the solid waste expelled from the fish tank and into the grow bed.
However, it is important to note that not all aquaponics methods use aquaponics grow media, like the raft system and nutrient film technique (NFT), where the plants are grown in floating rafts and PVC pipes.
Factors to Consider in Choosing Aquaponics Grow Media
In choosing the suitable aquaponics grow media for your system, there are several options you can choose from. But for the success of your aquaponics system and in order to choose the right grow media for your system, consider the following factors.
The recommended grow media for aquaponics are ½" to ¾" in size, with an adequate surface area for colonizing bacteria. Too small grow media might clog your system. While too large grow media might cause air gaps that can affect plant growth.
Weight is an essential factor in choosing your media. If you have smaller or flimsy aquaponics bed setups, ensure that your grow media is not too heavy or bulky.
Your system might physically collapse if the structure cannot support the weight of your grow bed. Choose a grow media that is light to medium weight because if your grow media is too light, it might float and clog your system, and if it's too heavy, it might become unmanageable in the long run.
Monitoring and balancing your system's pH level is something you need to do regularly. The pH level of your system must be within the ideal range. That is why it is crucial to choose a pH-neutral grow media.
Opting for pH-neutral grow media will allow you to manage the pH level of your system better. If you opt to use gravel or lava rock, it is good to do a test to see if they are pH neutral.
To test, simply wash your grow media thoroughly with water, place it in a container, and then cover it with vinegar. If you see bubbles, then your grow media has a high pH. If there are no bubbles, it means your grow media is pH neutral.
Easy on the Hands
You will handle the grow media with your hands when you place them in the grow bed and when planting your vegetables. Sharp grow media can damage plant roots and cut your hands as you tend your grow bed. So it is crucial to choose grow media that are safe and easy to handle.
If you are just starting an aquaponics system, you need to consider the cost of your grow media. Grow media prices vary depending on what type of aquaponics grow media you'd like to use. For example, hydroton is expensive, while gravel tends to be cheaper. It is better to check your budget first and then choose the grow media within your budget.
The Different Aquaponics Grow Media
Also known as clay pebbles, Hydroton is a (L.E.C.A.) Lightweight Expanded Clay Aggregate. Hydroton is one of aquaponics' most expensive grow media, but they are an excellent option for growing plants.
They are lightweight but heavy enough to support the plant and full of microscopic holes that provide good drainage, increase the surface area, and ensure plenty of nitrifying bacteria in your system.
Hydroton clay pellets are easy to maintain, porous, pH neutral, and reusable. The porousness and shape ensure that there is a proper balance of water and oxygen in the system. But they also tend to float when first used, which can potentially cause clogging in your pipes and filters, so be extra careful in using hydroton for the first time.
Many aquaponics growers widely use lava rock as grow media because they are lightweight and have plenty of surface area. Lava rocks are typically pH neutral, porous, and provide good drainage and aeration to the system.
While lava rocks are a popular grow media option in aquaponics, it also has some downside. Lava rocks have sharp edges that might damage your plant's root system or cut your hands when you handle them.
Another great aquaponics grow media is the expanded shale. Expanded shales are porous, pH-neutral, and contain air pockets that provide additional surface area for bacteria. Because expanded shale underwent a heating process, its edges are slightly polished, so it's easy on the hand and will not harm your plants' root system. Expanded shale is reusable and more affordable than other grow media, so they are also popular for aquaponics growers.
Gravel is the least expensive aquaponics grow media, but it's also one of the most problematic. Gravel does not hold water efficiently and has a lower surface area than other grow media, so it can be challenging to colonize bacteria.
If you decide to use gravel, look for pea-size gravel that has been polished to smooth out its rough texture. Lastly, always do a vinegar test on your gravel before using them in your system, as limestone is often present.
Growstones are a kiln-fired aggregate made from mixing recycled glass with calcium carbonate. They are lightweight, reusable, and porous like expanded clay but shaped unevenly. Growstone provides adequate moisture and aeration to the root zone while their surface creates an ideal place for beneficial bacteria to colonize.
The downside of using grow stones as grow media is that there is some debate over whether grow stones can alter pH in an aquaponics system and whether they will break down over time.
Which Aquaponics Grow Media is Best for You?
In choosing the best aquaponics grow media for your system, consider the factors you need to consider. Also, consider your system's size, budget, and availability of the grow media you want to use in your location. Make sure the one you choose has the ideal properties that are suitable for your system.
If cost is not an issue, the best grow media to use is the expanded clay, but if you're on a tight budget, choose expanded shale or lava rocks.
Tips on Using Aquaponics Grow Media
Here are some tips to help you use and establish grow media in your aquaponics system.
- If you're not using hydroton, it is best to test your grow media with vinegar before putting it in your system. Wash your grow media thoroughly with water, and place it in a container and pour enough vinegar. If you see bubbles, it means it has a high pH. Bubbles are the reaction of vinegar with limestone.
- Leave at least two inches of dry media to avoid algae growth. Twelve inches is the recommended grow media depth, but you should add an extra two inches on top to prevent algae or fungal growth.
- Clean the grow media once a year to remove solids and other waste to avoid clogging your grow bed. A clogged grow bed can develop anaerobic zones that can kill the beneficial bacteria. A clogged grow bed will also reduce the nitrification process and raise your system's pH. A high pH level is an indicator of a clogged grow bed.
Thanks for reading! We hope this article guides you in choosing the right grow media for your aquaponics system. For more aquaponics information, read our Ultimate Aquaponics Beginner's Guide. If you have experiences in using any grow media which can give valuable information and knowledge to others who are looking for the right aquaponics grow media, feel free to share them in the comment section below.