Often these types of systems are called flood and drain. The plants are usually grown in pots with their roots supported by a medium of perlite, Rockwool or expanded clay pebbles (Hydroton.) The pots sit in a plastic tray which in turn sits above a reservoir filled with nutrient solution. The growing tray must be higher than the reservoir because the system relies on gravity to do the work.

A pump in the reservoir is connected to the bottom of the tray. When the pump turns on, the tray fills with water. When the water level reaches a pre-determined height, through the use of the overflow fitting, the water falls back into the reservoir. When the pump turns off, the water runs back down through the pump into the reservoir. Poetry...

Most growers choose to control irrigation with a timer. A typical schedule would involve several short one-hour water cycles per day, but the duration and frequencies of watering cycles varies from one system to another and is dependent on the crop, the plant size and environmental conditions.

Ebb and flow allows for high density planting while providing a well oxygenated root system. The ebb & flow method supplies fresh oxygen to the root system of plants in two ways. First, as the tray is flooded with nutrient solution, carbon dioxide rich air is pushed out from around the root system. When the pump is turned off, the tray is drained and oxygen rich air is drawn down to the roots. This oxygen is then used by the plants until the next cycle begins.

Second, when the nutrient solution drains through the flow, it creates a splash upon impact, adding much additional aeration.
Click here to see how splashing water helps to aerate your reservoir. (note that the splashing has been artistically amplified - it doesn't really splash out of the reservoir in that manner.)

It is and Ebb and a Flow. A breathing in and a breathing out, the rhythm aerates your plants in diligent meditative cycles. Listen closely, through the babble of the water, you may hear your plants quietly saying "Om."

Drip systems are the most widely used hydroponic systems in the world. They are commonly used in commercial facilities for growing long term crops like tomatoes and peppers. Drip systems provide plenty of aeration (more than ebb and flow) because plant roots are never totally submerged, but are never allowed to dry out. There is also the additional aeration that occurs from water falling back into the reservoir.
Click here to see how this aeration works. (note that the splashing has been artistically amplified - it doesn't really splash out of the reservoir in that manner.)

Drip systems operate very simply. A pump has tubing connected to it which then branches off to smaller tubes feeding many plants. It works just like a drip irrigation system in your yard. Nutrient solution is dripped onto the base of each plant where it then trickles down through the grow media and into the roots and finally drains into the reservoir where it is reused.

A drip system may be left to run continuously or it may be turned on and off with a timer. A good standard to go by is on for an hour and off for an hour, however we suggest experimenting to see what works best for you and your plants.

Building your own Drip System
The great thing about drip systems is that they are very inexpensive, easy to build and totally modifiable. At GreenCoast, we find the following design works very well.

The system is based on the following: plants are in buckets filled with grow medium. The buckets sit in a tray which drains into a reservoir underneath. Inside the reservoir is a pump.

Connect 1/2" tubing to the pump, and use that as your main water line. You may run several 1/2" branches off this line. Use the 1/2" tees/elbows/connectors as appropriate to make your lines as smooth as possible. You don't want any kinks in the hose. Run the lines along the top edge of the buckets and end each line with a 1/2" compression end cap.

Connect drippers or drip rings to the 1/2" tubing by punching holes where you want the drip rings connected. Be sure that all the drip rings are facing down

Plug in the pump -- watch for any water which is landing where it should not. Adjust as necessary.

Nutrient Film Technique systems are some of the most productive available, and they are often the chosen method of commercial growing. Plant roots are grown in a light-tight and shallow channel. Nutrient solution is continuously circulated, flowing over the roots up to 24 hours per day. The name of this growing method was so coined in order to stress that the depth of the liquid flowing past the roots should be very shallow in order to ensure that sufficient oxygen is supplied.

A wide range of vegetables and ornamental crops may be grown in an NFT system. Depending on channel width, NFT is great for plants as diverse as tomatoes and lettuce. When choosing an NFT system, care must be taken to choose the correct trough size. Small 4 inch troughs are fine for most plants, but larger vine crops with extensive root systems could hinder nutrient flow, causing root rot and pathogen growth. Large commercial systems use wider troughs with greater flow capacity.

Aeroponics is an exciting improvement on hydroponics that has been shown to greatly increase yields. The growing environment is similar to a misty rainforest with plenty of oxygen and moisture. In Hawaii, orchids are often seen growing freely in the trees due to the level of humidity in the air. Aeroponics strives to create this environment at the root zone.

The roots of the growing plants are suspended in the air, and they are misted by high pressure sprayers. The sprayers break the nutrient into small particles and saturate the roots. The levels of oxygen in the water are kept high by the constant circulation of the water. Aeroponics is beyond the age we're in now-- it's in the space ages. Aeroponic techniques are being investigated by NASA.

This example is the most complicated reservoir set up we could imagine. We did this to cover all the bases, and show you some of the things you might be including with your own reservoir. Some variations follow.

Pump
The pump in this diagram is an external one, also know as a non-submersible pump. It sucks the water from the inside of the reservoir through the black hose, and disperses it at high pressure to a large hydroponic system. A smaller submersible pump is often used for small to medium systems.

Float Valve
You'll notice the float valve is attached to the right side of the reservoir, with a city water line leading to a water tap. This provides for automated water filling. Learn more about float valves

Aeration
Most reservoirs need to include some form of aeration. Oxygen is very important for healthy roots and aerated water provides bonus oxygen. We suggest using either an air pump, air stone or venturi, or a combination of all three. None of these is depicted in the picture below. The reservoir below was designed for an Aeroponic system - which is extraordinarily aerated and doesn't need the added oxygen. The other types of systems may need extra oxygen, depending on the type of growing media used. NFT and Ebb and Flows generally do require added oxygen.

Draining a Reservoir
Since draining the reservoir is a regular event (twice a month, if not every ten days to prevent salt buildup) it is important to plan for the easiest way to do it. The two waterlines on the right side, coming in and out of the reservoir, represent our reservoir maintenance lines. One is connected to a submersible pump, which can be turned on to drain the reservoir - it is connected to a drain on the other end.

Automated Nutrient and pH Control
These two lines (located on the left) go to a 'sample pot' for an automated nutrient/pH dosing machine such as the HydroGeneral or GHC-IV. This is used by growers who have better things to do than check their nutrient every day.

Two more PVC tubes (not depicted in this image) would enter the top of the reservoir. One would be for nutrient dosing and the other for pH.