Clay Pebbles vs Perlite

Clay Pebbles vs Perlite

So, you are super excited to grow your own vegetables in a hydroponic system! But here’s the thing: you are still unsure as to which growing medium is best to achieve a healthy garden.

Clay pebbles and perlite are two of the most widely used growing substrates for hydroponic systems. Unlike soil, these materials keep your garden free from any soil-borne diseases. They are also cleaner and more economical to use, since you can reuse both of them. 

However, each growing medium still has its pros and cons, depending on the type of hydroponic system you are building. 

So, let us do a quick clay pebbles versus perlite comparison, to help you understand which of these two growing media will work best for you.

The importance of hydroponic media

If you are new to hydroponics, you might think that any rock would be suitable to support your growing plants. But in reality, it is not! Choosing the right hydroponic medium is critical for a number of reasons.

Traditionally, we use soil to cultivate our greens, and it is from this soil that plants normally get their nutrients to grow and bloom. As their roots and stems begin to expand, plants will also need the soil to support their growing height and weight. 

In hydroponics, however, it is a different story. With this method, you are growing plants in a soilless medium. So how do hydroponically-grown plants get the nutrients and support they need to keep them upright? This is where soilless hydroponic media come into play. 

The role of hydroponic media is to help support the plant’s weight and keep it upright while it grows. It also provides the roots with access to nutrients and oxygen. These materials are usually light, coarse, and porous, and do not affect the chemical composition of the nutrient solution.

One of the benefits of using soilless media is that you do not need to worry about soil-borne diseases and pests. This means that your greens can grow faster, healthier, and produce better quality fruits.

Knowing how important hydroponic media are when it comes to growing your plants, the next question would be this – which one is best? If you search online, you will find enough different growing media to overwhelm a newbie gardener! There are also different types of hydroponic systems, each requiring a specific growing medium. But, for now, you do not need to know these advanced hydroponic techniques if you are just starting out.

The most common growing media, and the ones we recommend for beginners, are clay pebbles and perlite. These two materials each have their pros and cons, depending on your chosen growing system. Some hydroponics enthusiasts even have their own recipes using these two growing media to achieve better results!

Clay pebbles versus perlite – which is better?

Both the clay pebbles and the perlite are excellent choices when setting up a hydroponic garden. In fact, these growing media are also popular in commercial hydroponic systems. However, if you are setting up a home hydroponic system, you might be wondering which one is better for you. 

The best growing medium to use depends on the type of hydroponic system you plan to build. For example, perlite is best used together with another medium, like coconut fiber. Clay pebbles, on the other hand, can also be used as a standalone medium but have a low water holding capacity. If you are setting up an ebb and flow-type system, it is best to top your expanded clay pebbles with 50 percent coco and 50 percent perlite.

Another important thing to consider is the type of plants you want to grow. The growing medium must be capable of physically supporting your plants while providing a healthy growing environment. It should also allow sufficient water flow so that the plant roots can quickly absorb nutrients.

Other factors to look for when choosing a growing medium:

  • The size of your hydroponic garden
  • Water retention capability
  • Aeration properties
  • Cation exchange capacity (CEC), air-filled porosity (AFP), and water holding capacity (WHC)
  • Sanitation and reusability
  • Weight of the material
  • Cost

Before committing to either clay pebbles or perlite, you need to figure out which one is best for your chosen hydroponic setup. Let us dive into some more details about each of these media, to help you figure out which is the right one for you.

What are clay pebbles?

One of the most popular soilless media used in hydroponic systems is clay pebbles. Also known as hydroton or LECA (lightweight expanded clay aggregate), clay pebbles are actually expanded clay balls heated in a rotary kiln at 2,000 degrees Fahrenheit. The material is designed to be lightweight, porous, and convenient for harvesting. It is also made of organic substances that do not affect the chemical composition in the water, making this an ideal substrate for your hydroponic garden.

So, are clay pebbles good for plants? Yes, they are! In fact, clay pebbles can provide better aeration to the plant’s root system compared with soil or sand. Since clay pebbles have tiny pores on their surface, they are capable of storing nutrients so that they are available for your plants at any time. Hence, they assist in the proper uptake of the nutrient solution into a plant’s root system.

If you are thinking of setting up a hydroponic system using clay pebbles, we highly recommend the organic clay pebbles from Cz Garden Supply. Just be aware, though, that not all plants do best with clay pebbles. 

Let us explore, below, some of the pros and cons of using clay pebbles.

Pros of using clay pebbles:

  • Clay pebbles have high porosity which means water can flow easily through the material. This prevents the water from getting backed up in your hydroponic system.
  • Clay pebbles can be cleaned and reused, making them an eco-friendly solution. Although they are made of organic materials, they do not degrade easily. 
  • Clay pebbles provide good aeration to the roots, thus preventing root rot.
  • Clay pebbles are more economical to use for small-scale home hydroponic systems. 
  • Unlike with soil-grown plants, clay pebbles do not attract pests. The shape of the pebbles also makes it challenging for almost any type of bug to settle in.
  • Clay pebbles have a neutral pH, meaning you only need to monitor your water’s pH swings, which is easier to manage than a soil-based garden.
  • Since clay pebbles do not cling to plants, it is easier to plant and harvest without physical exertion.
  • Clay pebbles are sterile, durable, and stable. They can also be used ornamentally for your indoor and outdoor plants.

Cons of using clay pebbles:

  • Clay pebbles must be thoroughly cleaned before placing them in a hydroponics system. Otherwise, the dust and sediment can clog the pumps and pipes.
  • Cold temperatures can easily make clay pebbles brittle. Hence, they are not ideal for use in areas with cold climates.
  • Clay pebbles must be soaked until they are saturated. Otherwise, they will end up floating in your hydroponic solution, clogging the drains, pumps, filters, and other equipment.
  • Clay pebbles have poor water retention properties, meaning they will dry out pretty quickly. Hence, they are best used in deep water culture setups.
  • Clay pebbles can be very expensive if used in large-scale setups.

What is perlite?

Perlite is another substrate that is popular in hydroponics, because it is porous, lightweight, and low-cost. It is made by heating volcanic glass or silica in a kiln until it expands to 20 times its original size. Aside from hydroponic gardening, these small nodules also have several applications in the construction industry where they are used for insulation, ceiling tiles, and lightweight plaster.

What makes perlite useful in hydroponic setups is its excellent drainage capabilities. Aside from being used as a filler, it is also great at holding water while providing good aeration for the roots to breathe. Two of the most popular perlite brands for hydroponics are HARRIS and Cz Garden Organics.

While perlite is suitable for deep water culture and drip irrigation systems, it is not a great choice if you are building an aquaponics setup because it can contaminate the system’s water reservoir. The fish in the tank can easily suffocate on the fine particles, causing death and collapse of the entire system.

Pros of using perlite

  • Perlite has great air-holding capacity, allowing the roots to breathe and preventing root rot.
  • Perlite is sanitary and highly resistant to fungal infestations.
  • Perlite is non-toxic and reusable.
  • Perlite is cheaper than clay pebbles, making it a more economical option for larger setups.
  • Perlite has a lighter weight than clay pebbles even after being soaked, meaning it is easier to move or manipulate it.
  • Similar to clay pebbles, perlite also has a neutral pH. This means it will not disrupt plants that are sensitive to pH swings.
  • Perlite has good water retention capabilities.
  • Perlite does not affect the nutrient solution of your hydroponic system as it does not contain any chemicals or nutrients.

Cons of using perlite

  • Perlite is not a renewable resource; it is a mined mineral.
  • Similar to clay pebbles, perlites must be cleaned thoroughly to avoid dust and particles from contaminating the hydroponic system.
  • Some plants with aggressive root systems can cause blockages in this substrate.
  • As mentioned previously, perlite is not a suitable growing medium for aquaponics systems due to its tendency to suffocate and kill the fish in the tank.
  • Perlite is not ideal for ebb and flow systems since it is easily washed away by flowing water.
  • Perlite can float in water due to its light weight, and possibly clog your hydroponic system. Hence, it is best used in combination with other growing media such as coconut fiber.


Choosing the right growing medium is essential for the successful growth of healthy plants in a hydroponic garden. In this guide, we have discussed the numerous attributes of both clay pebbles and perlite, and why they make excellent options for your hydroponics setup. Hopefully, after you have gone over the pros and cons of each of these growing media, you will have a better idea of which is the best choice for you.

Image: / CemSelvi