Continued....Right Grow Media

Please read my previous post regarding grow media (click here).  It was an introduction to this subject.  It will shed light on grow media and the characteristics of what you should look for when choosing a media.  As I stated before, what you choose will be dictated by what is readily available to you in your local area.  I live in Honduras and the only media available at the time of building my system was river rock or gravel.  A long as you properly test it before use, it is a good product to use.

Here are the top 5 grow mediums in use in aquaponics system.  I am not saying these are the only ones, but these are the main ones in use at the time of this writing.  You can look into other products, but I would highly recommend using my previous blog post on grow media as a guide.  The least thing you want to do is experiment with a new product and have to remove it because it didn‘t work in your system.

The list you see here is provided by uPonics.com

#1 - Clay Pebbles (LECA)

Lightweight Expanded Clay Aggregate (LECA) are balls of clay which have been processed at a super-high temperature to form a highly effective grow medium. It is one of the most popular media used in both hydroponics and aquaponics – and for good reason.

​Clay pebbles are lightweight yet heavy enough to provide good support to a plant. They are also pH-neutral, non-degradable, and release almost no additional nutrients into the water.

​Their highly-porous composition and spherical shape help to maintain a beneficial oxygen to water balance while also providing gardeners a smooth surface to work with (ie, they won’t cut your hands!).
A possible downside is the initial expense of purchasing bags of LECA. However, since this grow media is totally reusable, in the long run, clay pebbles are an investment that will serve you over the course of many grows and many years. Because clay pebbles have very few drawbacks and fit every criterion for a great aquaponics grow media, they are our top pick.

#2 - Expanded Shale

Like LECA, expanded shale is another great aquaponics grow medium. The silicon-based shale is mined, crushed, and then kiln-fired at high temperatures. The result is a porous, pH-neutral, and clean aggregate that is ready to use in an aquaponics system.
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Although slightly heavier than LECA, expanded shale has a lightweight profile which works well in aquaponics grow beds. Each stone possesses a large surface area for producing the bacteria necessary to convert ammonia into nitrates.

​Expanded shale has a slightly polished surface area, so – like clay pebbles – it’s easy on the hands and will not harm the root system of your plants. Additionally, shale is reusable and typically manufactured in the USA. For all of the positive characteristics of expanded shale, we rate it as #2 on our list of best aquaponics grow media.

#3 - Growstones

​Growstones are a kiln-fired aggregate made from mixing recycled glass with calcium carbonate. They possess many of the same positive characteristics of LECA and Expanded Shale –  lightweight, porous, smooth surface, and pH-balanced. Growstones provide beneficial moisture and aeration to the root zone and their large surface creates an ideal area for beneficial bacteria to colonize.

That said, growstones do have a few drawbacks. For one, plant matter is more apt to collect inside the pores of growstones than other media.

So while they are reusable, they should be thoroughly cleaned between grows to remove any plant debris.  Additionally, there is some debate over whether growstones alter pH in an aquaponics system and whether they can break down over time. We would advise you to soak your growstones for a few days before using them and test the pH until it consistently reads neutral. And if you are concerned that growstones may break down over time, just opt for LECA or expanded shale. For the aquaponics gardeners, growstones provide a problem-free aquaponics grow medium.

#4 - Lava Rock

Lava rocks have been used as a hydroponics and aquaponics growing medium for decades. They are lightweight and porous and provide beneficial drainage, aeration, water retention, and even trace elements to the system. And, like any good growing medium, lava rocks are pH-neutral.

​A notable disadvantage is their jagged texture. The sharp edges of lava rocks have the potential to damage the root system of your plants as well as cut your hands as you tend to your aquaponics grow beds.

​That aside, lava rocks have numerous beneficial aquaponics grow media properties and might be worth a shot if you don’t want to use LECA or expanded shale.

#5 - Gravel

Gravel is the least expensive aquaponics grow media, but it’s also the most problematic. For one, it’s denser than the alternatives. This may be acceptable for supporting taller plants (like corn), but not so well with smaller plants. It can be a challenge to locate the proper size gravel, but pea size and river gravel are the best options. Other drawbacks are that it does not hold water efficiently and has a much lower surface area than the alternatives, ​so it can be difficult to colonize bacteria and its bio-filtration capacity is reduced. 

​Lastly, always do a vinegar-test of gravel before putting it in your system, 

as limestone is often present. If you must use gravel, look for stones that have been polished down to smooth out its rough texture.

​I hope this list will give you some direction in the pursuit of aquaponics.  There are plenty of choices available.  Obviously, there are better choices over others.  But, it comes down to what is available and fitting within your budget.

Make sure you stay tune to our blog, we will have many other postings coming soon.  Also, check out our website, www.MorningStarAquaponics.com

Shawn Paul