Intro to Hydroponic Systems

By the urban gardener

Australia's online hydroponics supplies & indoor grow shop

Ebb and Flow Hydroponic System

Such system is also known as flood and drain. It presupposes the use of the pots placed on a plastic tray for the plants growing. The pots are filled with perlite (expanded clay pebbles as Hydroton, or Rockwool), which supports the roots of the plants. The tray is situated above the reservoir with nutrient solution. This is important, because such placement ensures the work of the whole system, which is actually triggered by gravity.  

Nutrient solution from the reservoir fills the tray with plants pots due to the work of the pump, which is attached to the bottom of the tray. Overflow fitting, fixed in the tray at a height that a gardener predetermines himself, does not allow too much water to enter the vessel. When the pump is off, all the water flows back into the reservoir through the pump, and later it is used to water the plants again.

The procedure of plants watering repeats several times a day, and it is controlled by a timer. Usually, these are short one-hour cycles. However, a gardener may choose some other schedule, taking into account the type and size of the grown plants, environmental conditions, as well as the hydroponic system used.

Ebb and flow is suitable for high density planting. One of its main benefits is good oxygenating of plants roots. First of all, when filling the tray, water pushes out old air with carbon dioxide from around the roots. Later, when it goes back down into the reservoir, fresh, oxygen rich air is delivered to the roots. This air is available for the roots till the next irrigation cycle. Moreover, when water runs down and reaches the reservoir, it splashes, which creates its additional aeration.

Drip Hydroponic System

Drip systems belong to those most frequently used worldwide. They are often employed in commercial facilities and provide good yields of long-term plants and vegetables as, for example, peppers and tomatoes. Drip hydroponic systems offer even better aeration rates than flood and drain systems, due to the partial dipping of the plants roots, which are, at the same time, protected from drying out. Additional aeration, created by water splashing down into the reservoir, is also present.  

Drip hydroponic systems have something in common with the yard drip irrigation system. The ducting from the pump branches out into smaller tubes, which supply nutrients to many plants. Nutrient rich water drips near the base of each plant stem. Then it flows down into the growing medium, where it can be easily absorbed by the roots of the plants. The access of the solution tickles down into the reservoir.

Drip systems can be on all the time; however, many gardeners prefer to water the plants for an hour and then turn the system off for another hour. The systems are also controlled with the timers, set according to the gardener’s preferences. Often it is recommended to experiment with the system to find out what schedule is best for the particular kind of plants you are growing.   

Building Your Own Drip System
It is very easy to build and modify the drip systems. In addition, they are inexpensive. One of the most convenient ways is to arrange your system as follows: the plants are grown in the pots with the growing medium. Individual pots are then placed on a tray, underneath of which is a reservoir for nutrient solution. The latter is supplied with the help of a pump.

The main tube, connected to the pump, can be ½ inches wide. It is also possible to use several similar tubes to branch off this line. Try to make the ducting as smooth as possible with the help of the ½ inches connectors/tees/elbows, avoiding kinks. Do not forget to block each tube with ½ inches compression end cap. Then put the tubes along the top edges of the pots.

Next step is to connect the drip rings to the ducting. For this purpose define the places where the drippers should be and pierce the holes there. Upon connecting the drippers make sure that they are facing down.

Plug in and turn on the pump to check whether the system is working properly.

Nutrient Film Technique (NFT) Hydroponic System

For commercial growing, where high effectiveness is expected, nutrient film technique is most widely used these days. In the systems of this type plants grow in shallow channels, where the solution, enriched with nutrients, is circulated constantly all the day round. It is important to ensure shallow depth of circulating liquid, so that the plants’ roots receive enough oxygen as well.

Nutrient film technique or NFT can be used to grow a wide variety of vegetables, such as tomatoes and lettuce, and decorative plants as well. It is important to choose the proper trough for your NFT system. This choice depends on the type of the plants, which are to be grown. In most cases 4 inches troughs are suitable, but if you plant to grow plants with large and extensive roots, it is reasonable to use larger troughs in order to prevent obstructions in nutrient flow and roots rotting. In commercial growing, troughs of larger sizes are commonly used.

Aeroponics Systems

Aeroponics exerts to mimic the natural environmental conditions, sometimes observed in Hawaii, where it is possible to see orchids growing in the trees thanks to the high level of humidity. This way of plants growing features much moisture and oxygen around the roots and in the grow room, which if arranged wisely promotes rich crops. 

The method ensures plants growing with the roots suspended in the air. They are continuously sprayed with high pressure sprayers, which task is to mist the plants roots with the tiny drops or particles of the nutrient solution. The latter contains high levels of oxygen due to the constant circulation.

Being the newest and the most miraculous way of growing plants, aeroponics is investigated and developed by NASA. 

Reservoir Parts

We will describe all the parts of the reservoir set given on the picture to give the detailed information about their functioning and correct usage. This reservoir is one of the most complicated; however, you may choose more simple variations.

Pump
The reservoir on this picture has an external pump, often called a non-submersible pump. It sucks nutrient solution up from the reservoir through the black hose and pulls it at high pressure to a large hydroponic system. Small and medium systems may utilize smaller submersible pumps.

Float Valve
This reservoir set has a float valve fixed on the right side of the vessel, which is connected to a water tap with a city water line. Therefore, automated water filling is featured here.

Aeration
The described reservoir is designed for the Aeroponic systems; thus, it contains no means of the additional aeration of the water, as plants grown with Aeroponics techniques do not require it.

On the other hand, other methods of plants growing (e.g. Ebb and Flows or NFT) need to implement some type of additional roots aeration. Nutrient solution should also be aerated to supply not only nutrients to the plants, but oxygen as well. It is possible to use air stone or venture, or an air pump to increase oxygen availability in the water.

Draining a Reservoir
Salt buildup may become a significant problem if the reservoir is not timely drained. It is usually recommended to do it every ten to fourteen days. To ease the process you may use two waterlines specifically designed on the right side of the reservoir to fulfill the maintenance of the vessel. The lines come in and out of the reservoir; one tube is attached to the submersible pump and to the drain on the other end; thus, it is used to drain the vessel. The second duct is meant to refill the reservoir, and it is connected to the water tap with one end and to the reservoir on the other.

Automated Nutrient and pH Control

There are two lines on the left side of the reservoir, which are connected to a “sample pot” on the nutrient/pH dosing machine. The latter is used by the gardeners to automatically check the levels of pH and nutrients in the water. The examples of such machines are GHC-IV and HydroGeneral.