Choosing the right grow media is an essential part of aquaponics system. With so many types of grow media available, it’s difficult to know what will work best for you.
In aquaponics, your choice of grow media will have a huge impact on your overhead costs, especially in the beginning. You must choose the grow media that suits both the needs of your plants and the needs of the system to have a successful aquaponics system.
What is Grow Media?
Grow media supports the structure for plants in aquaponics system. In order for a plant to grow well and become established, it needs a strong root structure for it to absorb the nutrients it needs and to ensure it remains in an upright position. Grow media also serves as a surface area for bacteria to thrive inside your grow bed and acts as a filter for the solid wastes as it is expelled out of the fish tank and into the grow beds. Grow media also gives worms a comfortable habitat to live in and serve as an exchange for oxygen and moisture. (1)
Factors to Consider in Choosing Aquaponics Grow Media
It is important to consider grow media size, if it is too small, it might clog the system and large grow media might cause air gaps, which will affect the growth of the plants. The ideal grow media is ½” – ¾” in size and has a good surface area for bacteria. (1)
Easy On The Hands
Sharp grow media can damage your plants’ roots and can cut your hands as you tend your grow bed. Choosing a grow media that is easy on the hands and that you’re happy to work with. (2)
Some grow media can alter the pH of your system and can hurt your fish and limit your plants’ growth. It is important to control the pH level of your system and choose fish and plants that have a similar pH range. It is also a good idea to test your grow media with vinegar before you put it in your system. Wash your grow media thoroughly and place in a container with enough vinegar to cover your grow media. If you see bubbles, it means the pH is on the high side, no bubbles means the pH is neutral is which is ideal for your system. (2)
It is important that your grow media will not break down and decompose in your system. This can damage your plants. (2)
It’s important to consider the cost and to balance your budget against your expected result. Cost differs depending on which type of grow media you would like to use. (2)
Good Surface Area
The greater the surface area of your grow media, the more room for your bacteria and the better for your system. Different grow media offers different surface areas. Choose what suits your system. (2)
1. Clay Pebbles
Also known as expanded clay, clay pebbles are a Lightweight Expanded Clay Aggregate (L.E.C.A). They are lightweight but heavy enough to give support to the plant.
Clay pebbles are a great growing media option; full of microscopic holes which
provides good drainage while holding enough water to give optimum growth for your plants. These holes increase the surface area of this grow media and provide plenty of nitrifying bacteria for your aquaponics system.
However, since this grow media is reusable, clay pebbles are a good investment and because of its few dis-advantage, clay pebbles are great for aquaponics system and a our top #1 pick for growing media. Expanded clay is pH neutral, easy to maintain, porous and ensures a good balance of water and oxygen to avoid dry conditions. Poor quality clay pebbles tend to float when first used, which can cause blockage to your pipes and filter.
Recommended Expanded Clay Pebbles Products:
This natural clay is mined, formed into pellets, then kiln fired at high temperatures to cause the clay to expand into a tough, lightweight balls.
LECA clay simultaneously allows excellent aeration and keeps water for root health.
100% natural expanded clay. Inert, pH-neutral, clean & decorative.
Hydrofarm Growt Clay Pebbles
Made from 100% natural clay, stable in both pH and EC.
2. Expanded Shale
This is a natural shale which is heated to a high temperature which result in creating hundreds of tiny air pockets inside which increase the porous nature of this grow media and creating the surface area for bacteria to colonize.
Expanded shale is porous, a pH-neutral, reusable, easy on the hands, and will not harm the root system of your plants.
Each stone has a large surface area for producing the bacteria for your aquaponics system.
This product is as cheap as a pea gravel, making it an attractive for aquaponics making it our #2 in top growing media for aquaponics.
Recommended Expanded Shale Products:
Great way to loosen and aerate poor clay soils
Encourages better root development & growth
3. Lava Rock
Lava rocks are lightweight and porous and provide aeration, beneficial drainage, and water retention. They are also pH neutral. Lava rock has sharp edges that might damage the root system of your plants and cut your hands. However, lava rock has many benefits as an aquaponic grow media and might be worth a try, if you don’t want to use LECA.
Recommended Lava Rock Products:
A great decorative moisture retainer for potted or bedded plant.
Great for aeration.
4. River Rock
River rocks are round and have been shaped by river flow. This is one of the cheapest options for your aquaponics system. We recommend medium grade river rock as small river rocks might clog your pipes and filter.
River rocks are a good medium for anyone who is just starting their own aquaponics system but make sure your grow bed can handle the weight of your river rock. It is also important to check the pH of your river rock before using because there is a high probability that it might have limestones in it.
Recommended River Rock Products:
Screened and spray-washed with water only.
We hand-pick only the highest quality pebbles.
This river rocks are naturally lightly polished for a smooth effect.
5. Pea Gravel
Gravel is one of the least expensive grow media but gravel does not hold water efficiently and has a lower surface area than other grow media, so it’s difficult to colonize bacteria and the bio-filtration capacity is reduced. It is also important to do a vinegar test on your gravel before using it in your system, as limestone can be present sometimes. Look for polished stones with smooth textures when you use gravel.
Recommended Pea Gravel products:
Great Gravel for plants.
100% granitic gneiss (no limestone!)
Use in Water features, Aquariums & ponds
Thanks for reading! Feel free to ask your questions in our comments section. You can also share your experiences in using any growing media which can give valuable information and knowledge to others who are looking for the top growing media for aquaponics.