Why You Shouldn’t Use Construction-Grade Clay Pellets

By Kent Gruetzmacher
Published: September 23, 2020 | Last updated: April 30, 2021 02:22:51
Key Takeaways

Clay pellets are a popular medium for hydroponic growers, however, cultivators need to make sure they aren’t buying construction-grade pellets. Kent Gruetzmacher explains the pitfalls of using the wrong pellets.

Do-it-yourself (DIY) hydroponic gardening is a rewarding, pleasurable pastime. To this end, designing your own setup (as opposed to buying a kit) saves money on supplies while also teaching many of the nuances of hydro growing. As many DIY gardeners know, the design process consists largely of weighing your options on equipment and assessing your buying choices.


While hardware stores can supply some DIY hydroponics needs, certain items still require a trip to the grow shop. While it’s often fun to try new things and save money, there are certain elements of your hydro setup you simply can’t skimp on.

When designing a hydroponic garden, one of the most important choices will be deciding on a cultivation system. Within this frame, many hydro growers opt for clay pellets as their substrate of choice. Yet, there are many clay pellets on the market, with some proving better suited for horticulture than others. Of importance here is the notion of avoiding construction-grade clay pellets in your hydro setup.


What are Clay Pellets?

Both the indoor gardening and construction industries utilize clay pellets referred to as “LECA clay.” The term LECA is an abbreviation for “lightweight expandable clay aggregate,” which is also sometimes referred to as “expanded clay.” The standout feature of LECA clay is how it is formed, with the material expanding into extremely lightweight pellets when heated at more than 2,000°F. Interestingly, this extreme heat causes the clay to expand with air pockets, giving LECA its signature light mass.

Read also: Reuse, Reuse, Reuse Your Media

Clay Pellets for Hydroponic Growing

Clay pellets for hydroponic growing are made with the same process as all LECA clays. However, special attention is paid in manufacturing these pellets so harmful materials aren’t accidentally mixed with the clay. As such, clay pellets found at hydro stores are considered food grade because they are free of harmful impurities. Therefore, store-bought clay pellets can support a plant’s delicate root system without exposing it to harmful impurities.


There are many motives for choosing to grow crops in clay pellets.

To begin with, because they are lightweight and porous, clay pellets retain water while also allowing for excellent root zone drainage. Also, many growers prefer clay pellets because they are considered pH-neutral and won’t cause imbalances in nutrient mixes. Finally, clay pellets are extremely durable and can be reused many times as long as they are cleaned between harvests. While these factors doubtless make clay pellets attractive for hydro growing, it’s important you purchase the correct LECA clay products for your needs.


Issues with Construction-Grade Clay Pellets

On the macro level, construction-grade clay pellets are made in the same way as other LECA clays. However, construction-grade clay pellets are produced specifically as an ingredient for lightweight concrete. Because concrete mixes don’t require food-grade purity, this LECA clay is manufactured with few controls in place regarding contaminants.

LECA clay pebbles are formed from standard clay that is extracted from the ground.

Generally, for construction-grade pellets, LECA producers will utilize the most convenient clay source to their manufacturing facility, regardless of quality.

Read also: Substrate Selection & Moisture Management: What You NEED to Know

Therefore, because there is a lack of quality control on this clay, it could contain impurities that are harmful for plants. Similarly, with a disregard for the good manufacturing practices (GMP) that come with food-grade pellets, construction-grade pellets can also be stored with potential contaminants such as concrete, limestone, and mortar.

The contaminants found in construction-grade clay pellets can lead to devastating pH imbalances in your hydroponic setup. To this end, overabundances of minerals such as limestone can cause unpredictable rapid spikes in pH levels that can prove toxic for plants. Even more, because it is difficult to determine the precise mineral composition of construction-grade pellets, troubleshooting a hydro system with them in play is virtually impossible.

There is also a concern that the inconsistent sizing of construction-grade clay pellets could cause problems in a garden. Unlike hydro pellets, construction-grade pellets are not sized with cultivation purposes in mind. Therefore, if pellets are too small, they may pack too tightly and choke the rootzone off from valuable aeration. Conversely, oversized pellets may absorb too much water and wreak havoc on the water levels of your hydro system.

Stick to What’s Proven

DIY hydroponics can be fun and educational. However, there are certain elements of your setup where you should stick with proven methods. Of these, it’s vitally important to use cultivation mediums that are known to work successfully in hydroponics. In the case of LECA clay pellets, it seems you can’t beat the quality and reliability of products that are engineered specifically for horticulture.

Read also: How to Grow with Coco Bricks

One of the most attractive elements of hydroponics is the amount of control it allows you over your garden. To this end, savvy hydro growers can make precise choices on nutrient regimes and quickly pivot with imbalances of pH. Unfortunately, adding a wildcard to your hydro setup like construction-grade pellets removes many of the controls that have come to define hydroponics. While it’s great to save money on our gardens and try new things, sometimes it’s best to follow proven standards.


Share This Article

  • Facebook
  • LinkedIn
  • Twitter

Written by Kent Gruetzmacher | Writer, Owner of KCG Content

Profile Picture of Kent Gruetzmacher

Kent Gruetzmacher MFA is a Colorado-based writer and owner of the writing and marketing firm KCG Content. Kent has been working in the cannabis and hydroponics space for over a decade. Beginning in California in 2009, he has held positions in cultivation, operations, marketing, and business development. Looking specifically to writing, Kent has worked with many of the leading publications and marketing agencies in the cannabis space. His writing has been recognized by such icons as Steve D’Angelo and Rick Simpson.

Related Articles

Go back to top
Maximum Yield Logo

You must be 19 years of age or older to enter this site.

Please confirm your date of birth:

This feature requires cookies to be enabled