How to Make Hydroponics Clay Pebbles
Have you ever wondered how to make hydroponics clay pebbles? If so, you are not alone. But is it even possible without sophisticated equipment? DIY projects are fun and often save you money, but not all of these types of experiments are successful and practical. We will first examine the benefits of clay pebbles as a growing medium, and then show you how to make hydroponics clay pebbles at home if you want to give it a go on your own.
One of the first decisions you will have to make before planting your new crop is the choice of a growing medium (or substrate). As you may have read in our hydroponics growing medium page, growing media may be used to sprout seeds (or cuttings) before transplanting, and it is mostly used to give hydroponic plants an anchor for its roots after transplanting to into a hydroponics system. Not only does the grow media acts to support the plant, but it also provides a way to oxygenate and hydrate the root zone. Clay pebbles are quite possibly the best grow medium for hydroponics because it fits all the criteria you want in an effective grow media.
Lightweight Expanded Clay Aggregate (LECA) – often referred to Hydroton or clay pebbles – consist of balls of clay that has been super-heated (in a rotary kiln) from anywhere between 1100 to over 2000° F. This process causes popping, which creates the pebbles’ characteristic pores. These pores, in addition to the spaces between pebbles, make Hydroton a light and airy growing medium that provides water, air, and drainage. They are pH-neutral, non-degradable, and do not add any additional nutrients or substances into the nutrient solution within a hydroponic system reservoir. Clay pebbles are also reusable, which makes the initial cost easier to stomach. Because of their advantageous properties, clay pebbles are very popular with both hydroponics. In fact, clay pebbles are also the most popular aquaponics grow media as well.
- Unlike perlite and sand, hydroponics clay pebbles have abundant space between them for proper percolation (flow of nutrients through the growing medium). Even if debris, algae, or microbes cling to the pebbles, there is little chance of blockage.
- While clay pebbles can’t compete with perlite’s air holding capacity (AHC) they do have the ability to hold air bubbles and, thus, prevent oxygen-free zones.
- Although clay is an abundant, environmentally-friendly medium, businesses strip-mine it for commercial sale. Strip-mining is not environmentally-friendly; however, you don’t have to feel guilty if you reuse your clay as many times as possible. If you ever need to discard clay pebbles, crush them first so that they break down faster.
- Clay pebbles are reusable. Just wash off any build-up, especially organic build-up, and you can reuse it many times.
- Since Hydroton is a loose medium, it is easy to work with when transplanting or harvesting plants.
- Clay pebbles are relatively smooth, but they provide sufficient biological surface area (BSA) for growing the colonies of microbes that keep a system’s nutrients responsive and stable.
- Since clay is inert, it more pest-resistant than organic media. Again, wash off organic build up after each use.
Cation Exchange Capacity (CEC) is a measurement used to estimate the ability of a growing medium to attract, retain, and exchange certain ions from nutrients.
Since Hydroton pebbles are high in CEC, they can develop a white coating from the salt residue left by nutrient solutions. This can eventually kill your plants. To prevent this, regularly remove plants from pots and rinse before replanting or flush your system. Always use pH balanced water to rinse and soak pebbles. Use “Up pH” and “Down pH” products as necessary.
- Water holding capacity (WHC) is not as good with clay pebbles as with some other media. Since Hydroton tends to drain and dry out quickly, you may need to water more frequently. However, if you live in a cool climate, are growing drought-resistant crops, or have an irrigation system, this will not be a problem.
- Because Hydroton pebbles will float until they become saturated, they may get sucked drain lines or filters and cause a blockage. Small growers can avoid this by presoaking them.
- Some people don’t like the mess that the red dust from commercial Hydroton makes. Others say that those who don’t want to get dirty shouldn’t be farmers!
- Hydroton can be a costly option. If you live in an area with local sources of clay, I urge you to investigate making pebbles at home. Many people make clay seed balls. These are the same as Hydroton, except that the clay is not heated. See Getting and Processing Local Clay. Also, keep in touch with grower groups (such as Backyard Aquaponics forum) to exchange ideas and information on all things hydroponic.
The clay pebbles used in hydroponics are produced by aggregate companies. They mine the clay from the ground, crush it with huge grinding machines, and then essentially roast the clay (to expand) in massive rotary kilns under the extremely high heat of 1100 to up to 2000 degrees. So if you thought it would be an easy task to replicate how large aggregate companies produce their clay pebbles, guess again! Scour the internet and you will find virtually no DIY instructional videos on how to make hydroponics clay pebbles. Why? It’s just easier to buy your supplies online than to invest thousands of dollars and countless hours trying to make your own with this type of (potentially dangerous) equipment. However, if you want to experiment and give it a try, the following may be a way to go about it.
Note: We do not know if anyone has tried this method, so proceed at your own risk. If you do, let us know how it works!
1. Research sources of natural or commercial clay in your area. Potters are your best friends in this endeavor. Commercial Hydroton consists of a special aggregate, but I’m guessing that the clay used in making pottery will work too. Suppliers will give or sell you a small sample for testing before you commit to a larger amount.
2. If you can rent or borrow a rotary kiln, you can load clay in large amounts. Adjust the rollers (crushers) to form pebbles about one inch in diameter.
3. If you can’t get the use of a rotary kiln:
- Form clay into pebbles (about 1 inch in diameter) by hand. You can roll clay into long strips (or use an extruder), then cut it into smaller pieces to speed up this process. Your pebbles do not have to be perfectly spherical.
- Put pebbles in a pottery kiln or other heat source capable of reaching 2000° F.
4. Heat pebbles until they form bubbles and the bubbles break. The time it takes for this to happen depends on many factors. A potter of my acquaintance always fires her work overnight, then lets it cool for 8-10 hours.
5. Soak your pebbles. Then pat yourself on the back. You are one step closer to being off the grid.
1. Rinse before using to remove any dust or debris that might clog filters or drippers.
2. Soak for 6-24 hours before using. Make sure that a 3-inch radius around all plants remains saturated.
3. While soaking, add a nutrient solution. Mix a solution with one-fourth to one-half of your usual concentration or use a solution with an electrical conductivity (EC) of .4 or less.
4. After harvesting, recycle pebbles by removing old roots and rinsing with pH balanced water. Some gardeners recommend sterilizing pebbles with bleach, steam heat, isopropyl alcohol, or hydrogen peroxide. The important thing is to try and make sure that your Hydroton does not carry any impurities from one crop to another.
Beginners may want to start seeds in another medium, such as rockwool or crushed Hydroton, to reduce the need for frequent watering. To use clay pebbles:
1. Fill net pots, about 1.5 to 2.5 inches in diameter, with presoaked pebbles.
2. Place seeds on top of pebbles. If indicated by the type of plant, cover the seeds with pebbles as well.
3. Place these pots under a humidity dome and use misters to keep plants hydrated. Bursts of mist lasting 4-10 seconds every 2-3 hours should cause seeds to germinate. Be sure to keep the growing medium, as well as the plants, moist.
1. Low transplant technique. Fill a net pot about one-third to one-half full of presoaked pebbles. Plant a stem with a node about 1 inch below the top of the pebbles. The node should be close to the bottom of the pot. The node is where the new plant will sprout. Transfer seedlings to your hydroponic system.
2. Top drip method. Place cuttings directly into a deep-water culture (DWC) or ebb and flow(flood and drain) system. Position your drip emitters close enough to the freshly planted cuttings to ensure a sufficient flow of water and nutrients.
Growers tend to have their favorite growing media and to mix them depending on individual conditions. Alternatives to clay pebbles include oasis cubes, coconut fiber (coco coir), peat, composted bark, gravel, sand, lava rock, fiberglass insulation, sawdust, pumice, foam chips, polyurethane grow slabs, and rice hulls (husks). Depending on your location, you may be able to find or make some of these media at home. However, it’s much easier and often more effective to buy media manufactured specifically for hydroponic systems.
- We also recommend you research the alternatives:
- Growstone is a more environmentally-friendly medium than clay consisting of recycled glass.
- Rockwool (also called stone wool) consists of fibers spun from molten rock. Grodan is a popular brand. It has long been used as a growing medium and is still considered an industry standard among large growers. Because of its expense and difficulty of disposal (doesn’t decompose, can’t be reused), small growers are tending to choose other media. Soak it overnight before using.
- Perlite is a form of obsidian (volcanic glass) that has superior air holding capacity due to the cracks formed when it cools. However, it tends to shift or wash away when it comes in contact with flowing water. It can be used with other media to keep it in place. Always wear a dust mask when working with perlite and other dusty media.
- Vermiculite is a heat-expanded form of mica. Like perlite, it is lightweight and tends to shift in flowing water. Both perlite and vermiculite have good wicking properties, but perlite dries out quickly while vermiculite holds too much water. Therefore, the two products go well together.
- Another featured growing medium: Sphagnum peat moss. Sphagnum is one of the varieties of moss known as peat moss. Its advantages as a hydroponic growing medium include:-Completely natural and biodegradable
-Grows in highly absorbent strands that extend beyond their net pots to wick up water
- Its main disadvantage is that it decomposes over time and can shed small particles that can clog pumps and drip emitters. It is usually purchased in compressed blocks that need to be soaked about an hour before use.