Ebb & Flow - (Flood and Drain) System
The Ebb and Flow (Flood and Drain) system works by temporarily flooding the grow tray (root zone) with nutrient solution and then draining the solution back into the reservoir. This action is normally done with a submerged pump that is connected to a timer.
When the timer turns the pump on, nutrient solution is pumped into the grow tray. When the timer shuts the pump off, the nutrient solution flows back into the reservoir. The Timer is set to come on several times a day. Like in any hydroponic system the timer settings vary depending on the size and type of plants, the temperature and humidity, the type of growing medium used, as well as many other vareiables.
The Ebb & Flow (Flood and Drain) system is a versatile system that can be used with a variety of growing mediums. The entire grow tray can be filled with Grow Rocks, gravel or granular Rockwool. Many people like to use individual pots filled with growing medium, this makes it easier to move plants around or even move them in or out of the system. The main disadvantage of this type of system is that with some types of growing medium (Gravel, Growrocks, Perlite), there is a vulnerability to power outages as well as pump and timer failures. The roots can dry out quickly when the watering cycles are interrupted. This problem can be relieved somewhat by using growing media that retains more water (Rockwool, Vermiculite, coconut fiber or a good soiless mix like Pro-mix or Faffard's).