What is the best grow media for aquaponics? (Best hydroponic media bed)

The best aquaponics grow bed material

The aquaponics grow media you choose for growing your hydroponic plants is an important consideration. There are certain properties that aquaponics media bed material must possess. Let’s take a look at what these are…

What is the best grow media for aquaponics - Best hydroponic media bed

What is the best grow media for aquaponics in 15 seconds…

The best grow media for aquaponics tends to be clay pebbles. The reason for their popularity is that they are perfect for the plant’s roots and they maximise the surface area for beneficial bacteria to thrive. Clay pebbles are the most common hydroponic media bed material used in Aquaponics and are also known as clay balls or Light Expanded Clay Aggregate (LECA).


What is the best grow media for aquaponics?

Firstly, it’s important to point out that not all hydroponics grow media is suitable for aquaponics systems. The grow media you choose has to take into account that your ecosystem is designed for fish and other aquatic animals as well as plants.

For example, you mustn’t use any grow bed material that has limestone in it. Limestone is alkaline and this will affect the pH balance of the water and may even kill the fish.

Why an aquaponics system needs grow media

The grow media material we are discussing in this article is in the plant growing media that’s found in the hydroponics part of the aquaponics system. But why is grow media necessary?

If you consider for a moment that in a hydroponics system there’s no soil.

This means that in a hydroponics growing environment the plant roots need something to take hold. This is where the grow media takes the place of soil. But the grow media isn’t just about somewhere for the roots to take hold.

There are other functions the grow media has, just like soil does in traditional plant growing. Let’s take a look at the functions of Aquaponics grow media material in the hydroponic plant bed.

The main functions of the hydroponics media bed are as follows:
  • Serves as a support for the plant and root system to take hold.
  • Provides a surface for the bacteria to grow and perform their important nitrifying process, i.e. turning the fish waste into nitrates.
  • Serves as a filtering system for the waste contaminated water.
  • Helps with the aerating of the water to avoid the root system becoming an anaerobic environment.
  • Provides a safe environment for worms to live, which are present in some aquaponics systems.

With that in mind, let’s take a look at some key properties to look for when selecting the best aquaponics grow media for your aquaponics system.

Hydroponics media bed material properties to look for:

  1. Aquaponics grow media should be inert and pH-neutral.
  2. The size of your aquaponics grow media should be between 12-19mm (½” – ¾” inch) in size. This size provides for a good surface area for the colonising bacteria to grow.
  3. The grow media should be stable and should not decompose.
  4. You should avoid using limestone-based gravel as this will affect the pH of the water, making it more alkaline.

There are other considerations when you first choose your hydroponics media bed. Some of these include the following:

Aquaponics grow bed material considerations:

  1. The weight of the media bed material: Your aquaponics grow material shouldn’t be too heavy. Bearing in mind the next consideration in this list is the depth of the media bed. If it’s too heavy it can become unmanageable as a media bed. However, your aquaponics grow bed material can’t be too light either, otherwise it will float in the water.
  2. The depth of your media bed: The depth of your hydroponic media bed should be around 31cm (12 inches) deep. This is a sufficient enough depth to support the roots and provide the right environment for the bacteria to grow.
  3. Rinse your grow media when new: When you first get your bags of aquaponics grow media material, make sure to thoroughly rinse any dust and debris from the material to make sure your system is clean at the outset.

What are three common growing medium for aquaponics?

These are the most suitable aquaponics grow bed materials to use:

  1. Clay pebbles.
  2. Growstones.
  3. Lava Rock.

Let’s now take a look at each of these three common growing medium for aquaponics in more detail.

1. Clay pebbles (LECA)

Clay pebbles are possibly the most common growing media in Aquaponics. Also known as clay balls or as Light Expanded Clay Aggregate (LECA).

These balls of clay are made through a process where they are fired at a super-high temperature. Whilst clay pebbles are fairly lightweight, they are still heavy enough not to float. Clay pebbles provide good support for the plant roots and of course they are pH-neutral and non-degradable.

The added benefit of the clay pebbles is they are spherical in shape, which makes then smooth to work with and soft on the hands. But they also provide a great surface for the nitrifying bacteria to thrive so they convert the ammonia to nitrates for the plants.

More Reading: What is the process of aquaponics? (The step by step process in detail)

Clay pebbles are one of the more expensive aquaponics media bed materials, but as they are washable and reusable, this cost is a one-off initial investment.

2. Growstones

Growstones are similar to clay pebbles and are another popular aquaponics grow bed material. They are cheaper than the clay pebbles which is what probably makes it more popular.

As with all good aquaponics grow bed material, growstones are both sterile and pH neutral. However, having said that it’s still always a good idea to thoroughly wash your new growstone straight out of the bag before you use it in your aquaponics system.

Growstones are made of a lightweight material and are porous with a smooth surface, and are pH neutral. They have a large surface area which is ideal for beneficial bacteria to colonise. They are more likely to clog up than clay pebbles and will require a thorough clean in-between grows.

3. Larva Rock

Lava rocks have been one of the principle aquaponics media bed materials used for a number of years. They are lightweight and porous and offer good drainage and aeration. They are also pH-neutral too.

However, one of the downsides to lava rocks is they have a more jagged edge to them, which makes them not so great to handle when you’re washing them.

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Happy DIY aquaponics.

What is the best grow media for aquaponics? (Best hydroponic media bed)

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