Aquaponics Grow Media

credit to : Farm Tech Mart
link : http://farmtech-mart.com/grow_media

Although there is no soil in a hydroponic garden, the plants must still be anchored. There is a wide range of inert materials which can be used to support plant roots and we call them "growing mediums". Clay Pellets, Perlite, Vermiculite, Coconut Fiber and Rockwool are the most popular media. The hydroponic media that work best are pH neutral, provide ample support for plants, retain moisture, and allow space for good air exchange. The type of media you choose will depend on the size and type of plants you wish to grow, and the type of hydroponic system being used. 

1. Clay Pebbles (LECA) 

Expended Clay Aggregate pebbles (LECA) main use is as a hydroponic growing media in flood and drain and dripper hydroponics systems like the Wilma. Clay pebbles can also be mixed with other hydroponic growing media like Cellmax, Coco or Soil to give better aeration. To create better drainage when growing in pots add a layer of Clay pebbles in the bottom.

Many growers use clay pebbles as a hydroponic growing media because they have excellent aeration and drainage properties. Clay pebbles are a clean, ph stable, and can be reused a couple of times before they need to be replaced.

Flood and drain or a dripper system will deliver the fast growth rates and yields using clay pebbles.

The centre of a clay pebble is honeycomb to make it light weight and the outside of a clay pebble is covered in a thin layer of solid clay making them suitable for use in hydroponics.

Tired of looking at dirty soil on the top of house plants in pots why not use some clay pebbles to make it look more attractive.

2. Perlite

Good old perlite! It's been around for years, mainly for use as a soil additive to increase aeration and draining of the soil. Perlite is a mined material, a form of volcanic glass that when rapidly heated to more than 1600 deg. f. it pops much like popcorn as the water vaporizes and makes countless tiny bubbles.

Perlite is one of the best hydroponic growing mediums around. Used by itself or as a mixture with other mediums. Perlite is commonly used with vermiculite ( a 50 - 50 mix is a very popular medium), and is also one of the major ingredients of soiless mix's. Perlite has good wicking action which makes it a good choice for wick-type hydroponic systems. Perlite is also relatively inexpensive.

The biggest drawback to perlite is that it doesn't retain water well which means that it will dry out quickly between waterings. The dust from perlite is bad for your health so you should wear a dust mask when handling it.

3. Vermiculite 

Vermiculite is another mined material. In it's natural state it resembles mica rock, but when quickly heated it expands due to the generation of interlaminar steam.

Vermiculite is most frequently used in conjunction with perlite as the two complement each other well. Vermiculite retains moisture (about 200% - 300% by weight), and perlite doesn't so you can balance your growing medium so that it retains water and nutrients well but still supplies the roots with plenty of oxygen. A 50/50 mix of vermiculite and perlite is a very popular medium for drip type hydroponic systems as well as ebb and flow systems. Vermiculite is inexpensive.

The major drawback of vermiculite is that it retains too much water to be used by itself. It can suffocate the roots of plants if used straight.

4. Coconut Fiber 

Coconut fiber is rapidly becoming one of the most popular growing mediums in the world. In fact it may soon be THE most popular. It is the first totally "organic" growing medium that offers top performance in hydroponic systems. Coconut fiber is essentially a waste product of the coconut industry, it is the powdered husks of the coconut itself.

There are many advantages - it maintains a larger oxygen capacity than rockwool, yet also has superior water holding ability than rockwool which is a real advantage for hydroponic systems that have intermittent watering cycles.

Coconut fiber is also high in root stimulating hormones and offers some protection against root diseases including fungus infestation. Dutch growers have found that a mixture of 50% coconut fiber and 50% expanded clay pellets is the perfect growing medium.

One word of caution about coconut fiber, you must be careful when you purchase coconut fiber. There is a commonly available, lower grade of coconut fiber that is high in sea-salt and is very fine grained. Lower grade coconut fiber will lead to disappointing results when used in a hydroponic system.

5. Rockwool

Rockwool is a very popular hydroponics growing medium. Rockwool is a porous substance that forms when a mixture of rocks, mostly basalt and dolomite, is melted at high temperature and specially processed. Given the material's neutral nature, it is used to build plant-growing medium granules or slabs, blocks, plugs, cubes, etc.

Rockwool provides roots with a good balance of water/oxygen As rockwool is composed of 97% air, it is easy to control the air/water ratio in it. Its porous quality also enhances root growth.

. Small cubes are used for starting seeds and cuttings, 3" or 4" cubes for small plants or intermediate growth, and slabs for larger plants. Rockwool can be used with continuous drip or flood and drain systems. Although it is possible to sterilize and re-use Rockwool, most often it is used only once.

More than 95% of all greenhouse vegetable production is carried out with the help of Rockwool -and for good reason. Like mentioned before, rockwool allows control over air and water supply, which are essential factors for plant growth. It also provides other feasible conditions to support a great crop, leading to consistency in plant production and yield, which is an important consideration in commercial harvesting.

Another pro is the easy availability of Rockwool products in a variety of shapes and sizes. This promotes the maximum utilization of Rockwool in various types of hydroponic set-ups.