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.

Aquaponics 'Claimed' Disadvantages

Claimed Disadvantages:
by Matthew McCarthy
credit to :sites.google.com/site/aquapanaponics/4-project-updates/advantagesanddisadvantagesofaquaponics

• Can be expensive to setup as the system requires pumps, tubing, and tanks/beds. This is certainly true though it doesn't necessarily need to be. A small backyard system purchased complete from an aquaponics retailer can cost over $2,000 installed and the larger backyard systems capable of feeding a family between $5,000 and $10,000. Though if you are willing to devote some (or a lot) of your own time and energy then I think similar systems could be built for 25-50% of these costs (this is my guestimate). Grow beds and fish tanks can often be obtained for free (in western countries) and gravel obtained from the local river, though components such as pumps and backup power supplies will still need to be purchased. 

• You need a green house to really have a good aquaponics system. I guess this depends on what type of climate you live in. A green house can be advantageous to provide heat in cold winters, protect the system from heavy rains and keep out pests. This is also true for soil based gardening.

• Setup requires technical knowledge of aquaponics systems and hence is possible to make mistakes. True - there are stories around of people who loose fish and give up on their aquaponics system early on and there is some knowledge required to establish the necessary bacteria within the system. In a lot of cases these failures are because systems have fish stocking rates that are to high. We have yet to stock our system with fish so I can not provide a lot of information from our personal experiences though the initial establishing of bacteria (known as cycling the system) was very simple and took a lot less time then the average system cycling time.

• Water needs to be constantly monitored to make sure the water quality is OK for fish. This is certainly the case during the first couple of months. After the system has matured water testing is usually carried out only once a week unless there are problems. Seems very complicated for the amount of fish I will get. Yes keeping a healthy environment for the fish is where most of the complexity lies within the system. Water needs to be free of toxins (especially ammonia and nitrite) and also have enough oxygen for the fish you are keeping. This can involve adding extra aeration sources and making partial water changes to improve water quality. Stocking fish at a lower density will in most cases reduce the pressures on a system and make it more tolerant to changing conditions and less likely to suffer from the above problems - though this means you will have less fish to eat.

• Aquaponics requires electric energy input to maintain and recycle water within the system. In most cases you will need to provide electricity to run a water pump and possibly aeration pumps as well. We run our 80w water pump for 5 minutes every hour to flood and drain our three grow bed buckets. As we currently run the pump day and night this amounts to 2 hours of usage a day - so similar to having a light in your house (with an old style bulb) on for the same length of time. We plan to add another three grow beds to the system so this will increase our electricity usage further. At this stage we have not made any attempt to optimize the flood/drain cycle so there may be opportunities to reduce the number of times the system is flooded each hour or to not run the system at night with little impact to plant growth. 

• If one or more components fail this could lead to the loss of fish and or plants. In this regard you are dependent on using reliable technology (and back up systems) to ensure that your fish, which require oxygen in the water, remain alive an healthy. Your plants are likely to be unaffected in the short term, as the growing medium will likely retain more then enough moisture, though if the fish are not provided enough oxygen, they can suffer and die. This is the same situation for aquaculture systems.

• You can't grow root crops. You can grow pretty much anything in an aquaponics system from fruit trees to root crops, though depending on the type of growing medium potatoes and carrots may grow into some weird shapes. Most people focus on growing leafy vegetables.

• Ok so you don't have to add fertilizer or nutrients but you do have to provide fish food. Yes you do, the fish eat the food and their waste is used to produce nutrients for the plants. Of course you also have to feed fish in an aquaculture system and in an aquaculture system fish waste is not used in such a productive way. Fish are some of the best animals at converting food into body mass (different fish species vary) and so are an efficient way of producing meat and protein. Most people buy commercially available fish food for their fish although many people supplement this feed by growing worms, duckweed and other plants and animals.

Aquaponics Presentation #2

BALANCING AN AQUAPONICS SYSTEM

There are several items that needs balancing in an aquaponics system 

1. Nitrate level ~ high: Nitrogen-eating bacteria converts Ammonia to Nitrate

2. Water pH level ~ 7.0 optimum 

3. Sodium salts concentration ~ low 

4. Iron (Fe) addition 

5. Fish feed 

   

BENEFITS OF AN AQUAPONICS SYSTEM

 

There are a lot of benefits of managing an aquaponics system, such as:

1. Conservation through constant water reuse and recycling 

2. Organic fertilization of plants with natural fish emulsion 

3. The elimination of solid waste disposal from intensive aquaculture 

4. The reduction of needed cropland to produce vegetable crops 

5. The overall reduction of environmental footprint for crop production 

6. Small efficient commercial installations can be built close to markets therefore reducing food miles

7. Small systems are easily setup and operated; thus everybody can try 

8. If many people in our country starts their own small aquaponics system at home;

            a) sell surplus harvest, good side-income source 

            b) use fresh food daily, increase in overall health 

Besides all the benefits and profits, one should be aware of its disadvantages, such as:

1. Initial expense to start an aquaponic project

2.The infinite number of ways to configure

3. Rely heavily on energy, technology & control

4. Have multiple 'single points of failure' where problems can lead to

complete loss of fish stock


***presentation continues into #3, refer older post***