Aquaponic Growing Medium Contributes To Aquaponic System

Are you considering which aquaponic growing medium is best for your home garden? If so, read this article as it is essential to make a plan for building and maintaining your aquaponic system.

Some popular aquaponic growing mediums are:

  1. Lava Rocks
  2. Hydroton
  3. Hydro Stones
  4. River Rocks
  5. Expanded Shale

What Is Aquaponics Growing Media?

An aquaponics growing medium can be natural or artificial material to support your plants. It does not contain soil, and it is one of the essential elements for plant health.

Spatially, grow media for aquaponics protects the plant roots and ensures the distribution among the plant’s bases on the settled arrangement.

That means your plant roots have enough room to absorb nutrients and reduce the risk of falling during bad weather.

In terms of growth aids, the medium helps increase the surface area for beneficial bacteria to grow inside the bed. To build an aquaponics system, you need bacteria that convert fish waste into plant nutrients.

Specifically, the ammonia in fish waste will be filtered by the grow media to become nitrite in the first step and then nitrate. This nitrate is the plant’s nutritions, so they call growing media “nutrient solution” for aquaponic systems.

Otherwise, the chemical metabolism from solid waste to nutrients requires a surface for the bacteria to attach to. The surface area is proportional to the number of bacteria and the metabolism process from ammonia to nitrates.

Accordingly, using grow media will help increase the surface area, creating great conditions for the best conversion of nutrients.

However, some aquaponics methods do not require growing media, such as a raft system or nutrient film technique (NFT). Therefore, when determining an appropriate growing medium, you need to understand what aquaponics method you use.

What you need to know about aquaponic grow beds and how to select the right rock:

Requirements For Choosing Aquaponics Grow Media

pH Level

For any plant growing system, you need to regularly monitor and balance the pH levels of the soil to create the best conditions for plant growth.

Therefore, you need media for aquaponics with neutral pH to efficiently manage the pH of the entire system.

Before placing grow media in your system, please check their pH. You can follow these steps below:

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Step 1: Wash the medium with clean water.

Step 2: Put them in a bucket, then cover with vinegar.

The results will show the pH level. If the reaction of vinegar is bubbles, the medium has a high pH. On the other hand, if no air bubbles are present, the medium has a neutral pH.

Also, to save time and avoid unnecessary trouble, let’s choose plants with a pH range of 7. It is the best range when the system is in operation.

pH level is the most significant factor, so you should be aware of some growth media that can change the pH of your system to avoid. For example, you should know the danger of limestone. (People usually only use limestone to raise the pH level.)

Surface Area

It is necessary to choose mediums with a large surface area to ensure bacteria can cling to them. As mentioned above, the surface area has a strong effect on how your plants metabolize nutrients.

Also, the smooth surface area is easy to handle. The grow media with sharp edges have the risks of damaging your plants, and they can even cut your hands while you’re tending them.

Therefore, let’s put safety first and choose a medium that has smooth edges to handle easily.


The growing medium must ensure that it does not spoil or decompose quickly in the aquaponics system. Decomposition reduces the surface area for bacterial attachment and causes clogging and anaerobic pockets for the growing media.

The conditions mentioned above will unarguably harm your plants and all your system.


Size is one of the basic requirements when choosing a medium. Large medium sizes will create air holes, affecting the growth of plants.

Meanwhile, too small ones do not have enough surface for bacteria to cling to.

Therefore, here is a rule of thumb for choosing the size: suitable aquaponics grows media should be ½ to ¾ inches.


You should know that adding growing medium aquaponics will increase the physical load of the grow bed system. If you choose too heavy mediums, your system may collapse physically.

It also is advisable not to choose a lightweight type because it will easily drift, causing a blockage in the system. Therefore, the suitable weight is medium.

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Price is always a crucial factor when considering a grow medium for aquaponics. Surveying the market, you will realize that Hydroton is the high-priced type, and the cheap one is for gravel or river rocks.

Think about the budget you can invest for a type of aquaponics grow, and then you can easily choose the right one for you.

Best Aquaponics Grow Media

Lava Rocks

Lava rocks are one of the popular choices for aquaponics grow media. They have an internal air pocket structure that makes their weight lighter than ordinary rocks. That also greatly increases their surface area and allows bacteria to cling to.

Lava rocks have a neutral pH, so they are suitable for pH management of the entire Aquaponics system.

However, the minus point is that they are pretty sharp, risking you cutting your hand if you accidentally touch them. The sharpness can also cause damage to the roots if you place them carelessly.


  • Great surface area
  • Lightweight but adequate
  • pH neutral


  • Sharpness
  • Easily damage plant roots


Hydroton is from an expanded clay product and is an excellent choice in supporting the growth of any plant. It has all the elements you need for a growing medium.

The micro-holes on the Hydroton’s stem help retain water for the plant and support good drain systems.

Not only that, these holes are the factor that increases the surface area of ​​this medium. It ensures increased levels of nitrifying bacteria for the aquaponics system.

Aquaponic Growing Medium Contributes To Aquaponic System
“Hydroton” by jasonawhite is licensed under CC BY 2.0

With its small size, light texture, and neutral pH, many people choose Hydroton for their system.

However, it also has certain disadvantages. Due to its lightweight, it floats effortlessly, causing blockages in pipes and filters. In addition, it is an expensive option.


  • Great surface area
  • Micro-holes to ensure the bacteria amount
  • Support keep and excess water for excellent drainage
  • pH Neutral


  • Expensive
  • Issue of filter and tube blockage for being too light

Hydro Stones

Hydro stones are an excellent choice to start building an aquaponics system. They are pretty light because of the porous internal structure, so you are completely assured of the bed system’s physical endurance when used.

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This stone also has a neutral pH, which aids in the management of the system’s pH. Moreover, its surface has many holes, so it is very suitable for the growth of bacteria.

However, there is one thing that you need to keep in mind while using these stones. Their surface has a texture similar to sandpaper, so you should be careful not to get scratched when handling them.

On the other hand, you need to check if aquatic animals in the fish tank below are comfortable with this medium.


  • Large and porous additional surface area
  • pH neutral
  • Multi-hole in surface for supporting bacterial growth
  • Lightweight


  • Not always available
  • Risk of being scratched by the rough texture

River Rocks

River rocks are the best media for aquaponics if you are getting started with this system. It is the highly popular and cheapest option.

Moreover, it has a smooth surface with a particle size that you will not worry about cutting off the hands accidentally.

However, you won’t want to choose the small-sized types because of the risk of clogging the planting streams. Small river rocks will block tree growth and affect bed distribution.

Besides, it’s necessary to test its pH before use because limestone increases the system’s pH.


  • Low price
  • Popular choice
  • Suitable for newbie


  • Small type blocks plant’s growth
  • Need to check pH before using
  • Slightly heavy

Expanded Shale

Aquaponic Growing Medium Contributes To Aquaponic System
“Shale” by kyz is licensed under CC BY 2.0

Natural expanded shale is suitable for aquaponics systems. It is created by a biological heating process with up to 2,000 degrees F that helps make the barrier of internal air pockets.

As a result, its surface strengthens, and the natural porous characteristics are what many rocks cannot have. This feature is beneficial for bacteria and the nitrifying process.

Additionally, this natural shale is very cheap and quite popular. Although the appearance looks rough, you can be assured as it doesn’t cut off your hand.


  • Cheap and popular
  • Lightweight
  • Beneficial for bacteria to nutrify
  • Plenty of surface area
  • pH neutral


  • The size is slightly big.


The aquaponic growing medium is essential for building a perfect aquaponic system. Therefore, it is advisable to research the suitable one supporting you the best.

By checking the information contained in this article, you certainly evaluate and choose for yourself the suitable medium.

Hopefully, you can build and complete your aquaponics system in the future with the most suitable growing medium.

Aquaponic Growing Medium Contributes To Aquaponic System
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Jill Sandy

I am a sustainable focus gardener. I love decorating my home backyard with beautiful landscape design and creative garden care techniques I develop myself.