The Ebb and Flow system (also called the flood and drain method) works by temporarily flooding the grow tray with nutrient solution for a designated amount of time and then draining the solution back into the reservoir. Most ebb and flow systems are set-up to flood the grow bed, the collection of plant pots (filled with growing media), for between 10 to 15 minutes, every hour or 2 hours. Ebb and Flow systems make use of grow media, such as perlite and vermiculite, rockwool or L.E.C.A., to support plant roots in the grow bed pots.
To run ebbs and flow hydroponic systems you will also need a pump and timer. The timer is connected to the pump, turning it on at intervals in order to pump nutrient solution into the grow tray. For a few minutes the roots are immersed then the timer shuts off and the nutrients drain back down to the tank, while simultaneously drawing oxygen to the roots. The ebb and flow timer is set according to the size and type of plants, the temperature and the humidity, as well as the type of growing medium used.
Ebb and Flow is a versatile system that can be used with a variety of growing media including the following:
Coconut fiber, rockwool and L.E.C.A. are the most popular grow media used with ebb and flow hydroponic systems because they retain more water then other types.
The ebb and flow system shares one disadvantage with the NFT system. Both pump based systems are vulnerable to power outages, as well as timer failures. If either the pump or timer fails, the plant roots will dry out and die without quick attention.
Ebb and flow is a popular hydro system because it allows you to grow a wide variety of plants at the same time or harvest plants individually in their own separate containers.