Unit 2. Part (B) Building a water system
In hydroponic systems, an important part is the delivery of water to the plants. Water can be supplied to the plant roots in a variety of methods.
Flood and drain
Having water dose the roots and then drain back out in certain times is called an ebb and flow system. It requires a nutrient tank where water is stored, a water pump to pump water from the tank to the plant container, and a timer to run the pump at preset time intervals.
Flood and drain also requires that the plant container retain some amount of water in the bottom to supply plants with extra water during the times that water is not flowing. This means there should be a water table in the system.
Flood and drain usually has a media for the plants that will be flooded when the pump is running and then slowly drained with the pump is not running. This supplies a plant root growing area with both water and air.
Illustration of a Floos and Drain System
NFT – Nutrient Film Technique
In NFT, the water is pumped continuously through the system. It also uses a nutrient water tank and a pump. Because water flows continuously, the pump is always on and does not require a timer.
Because the plant roots have a continuous flow of water, they do not need a water table and the plant growing area does not require media. The flowing water has enough air to support the part growth. Some systems supply air into the water with an air pump.
NFT plant containers can be much simpler than ebb and flow. Systems have been designed that are black plastic bags. Plants are placed through a top hole if the bag and nutrient water is trickled through the bag. Plant roots form a mat in the bag, and do not require any media.
Illustration of an NFT system.
In Drip irrigation nutrient water is delivered to the plant containers through a dripper. A dripper is a small piece of tubing that has a tiny valve on the end, and a spike to place the dripper in the media.
A drip irrigation system requires the plant have a media and the dripper is usually continuously supplied with nutrient water. If there is a nutrient tank, the drip system will also need a water pump to keep pressure high so the drippers will drip.
Illustration of a drip system.
There are other water delivery systems that are being tried. One is called an aeroponics, with is a system where water is spryed with air nozzles onto the plant roots.Another is a wick system where a wick (like a candle wick) is placed between the water below and the media above allowing water to come up from bottom.
Another, a type of flood and drain, will flood a whole room or tray with water and then allow it to drain back into the nutrient tank.
Revised: 1 May 2016