Different Types of Grow Media

Hands holding leca balls as growth media for an aquaponics system

Different Types of Grow Media

Different Types of Grow Media

October 07, 2021

If you are including a media grow bed in your system, then you will inevitably reach a point where you will have to choose between the different types of grow media. So, let’s take a look at the different options available to get you up and running as soon as possible.

Gravel

This is for our cost-effective farmers. Gravel is the most affordable type of grow media. It works well for taller plants however, smaller plants might struggle to form a stable root system. It’s important to use the correct size gravel, we recommend 19mm stone.

This type of media is very heavy, depending on the design of your system reinforcements may be needed. This is only problematic for biofiltration if it is the only source of filtration in your aquaponic system design.

When using gravel, you need to do the vinegar test to detect limestone and make sure you take the weight of the gravel into account when designing your system.

Gravel as an option for types of growth media in aquaponics

Lava Rocks

This pH-neutral type of growing media has been used in both hydroponics and aquaponics for many years. They are great for water retention, aeration and they provide trace elements to the system.

Although lightweight and porous, lava rock has a rough, ragged texture and this could possibly cause damage to the plants rooting system as well as make it difficult for a farmer to handle without getting a few battle scars along the way.

Lava Rock with a plant growing it is as a type of growth media for aquaponics

Expanded Shale

This type of grow media is a pH-neutral, silicon-based aggregate that is ready to use in your aquaponics system. Expanded shale is lightweight and the individual stones are large in surface area which is great for bacterial colony formation.

Additionally, shale is smooth so it’s easy on both the hands and root system. It’s also reusable and a great alternative for clay media.

Expanded Shale as a type of grow media in aquaponics

LECA (Clay Pebbles)

Lightweight Expanded Clay Pebbles or better known as LECA is definitely a personal favourite for hobbyists and home system owners.  type of growing media. This popular aggregate is lightweight but still provide the plants with the support they need.

LECA is highly porous to create the perfect environment for bacteria due to its ability to retain water and assist in aeration. We recommend using clay balls that are between 9-16mm.

One downside to this type of grow media is that the initial expense of purchasing LECA is quite steep. However, we like to look at it as an investment. LECA is non-degradable, reusable and is worthwhile for crops including ginger and galangal.

Hands holding leca balls as growth media for an aquaponics system

Our Grow Media Tips

  1. Over time, your grow media should be lifted and cleaned out to prevent any anaerobic bacterial growth.
  2. Get your size right: Make sure your media is small enough to prevent big air gaps but not too small that it clogs up your system.
  3. pH-neutral: finding the perfect pH balance in an aquaponics system is already a challenge so let’s not over complicate things with a grow media that could affect your pH levels.
  4. Non-degradable: make sure your grow media is in it for the long run. If the grow media breaks down it could cause many complications in your system.
  5. Clean your media before using: make sure you clean your grow media before adding it to the system to get rid of any dust or debris accumulated after manufacturing.
  6. Weight: You want to make sure that your type of grow media isn’t too heavy for your system that you struggle to work with it. However, you also don’t want a grow media that will float around your media bed when it floods.

And that’s everything you need to know about choosing between different types of grow media. If you are not sure that an Ebb & Flow media bed is for you then take a look at our blog post on Different Grow Methods  to learn more about other aquaponic system designs.