Flood and Drain & Ebb and Flow - Understanding Hydroponics Systems


Flood and Drain systems are another way of growing plants using hydroponics. There are many different types of this system available, all of which will produce great yields if used correctly. Flood and Drain is also known as Ebb and Flow. It is a very popular growing method among both commercial and home growers because it’s an easy system to use and quite easy to scale the operation up or down.

Some of the basic principles are the same regardless of which hydroponics system you use. It’s often the distribution of the nutrients and the mediums used that sets the systems apart. As with all hydro systems you will still need a reservoir of types to store the nutrient solution in but unlike an NFT system for instance it does not have to be a tank as such, some flood and drain systems utilise a water butt instead and are gravity fed to the plants instead of being pumped. For the purpose of this article we will look at flood and drain table using Rockwool blocks as a growing medium supplied by a pump.

As with other hydroponics systems you can use whichever medium you prefer such as Rockwool, Clay pebbles, Coir or Cocoa or there is even specially formulated mixtures of different substrates, there are so many that we will cover the different types in their own articles later.

How does Flood and Drain work?

For this instance the flood and drain system we are looking at needs trays or gullies to sit the plants on just like a standard hydro system. Unlike a passive hydro system, flood and drain feeds the plants in a unique way. The solution is pumped to the trays or gullies from the reservoir through a special two way valve but it is held within the tray for a certain amount of time, the solution basically floods the trays for a set amount of time, after a predetermined time (this can be set by a timer or float valve) the two way valve opens up and allows the solution to drain away leaving the Rockwool blocks or medium saturated in nutrient rich solution. This type of hydroponics system has its positives and also potential negatives, on the plus side the fact that the medium is not constantly in contact with the nutrient solution encourages good root growth and allows for a medium that’s oxygen rich but as with all systems that rely on pumps and valves to successfully circulate the nutrients they are liable to fail which could result in crop failure.

The above paragraph covers the basics of a Flood and Drain hydroponics system, there are many different types of this system available, some are manual some are automatic. One of the good things about Flood and Drain Hydroponics is that it’s easily scalable and flexible in which type of medium you use, it’s largely down to personal preferences. Some growers prefer to use Clay pebbles some prefer Rockwool or even cocoa coir. As with many things in the growing world the best results are found by trial and error so don’t be afraid to experiment with different mediums and nutrients until you find the correct things for you and your chosen plants.

The basics for nutrient solutions is pretty much the same for all hydroponics systems so please read our other article that covers making a nutrient solution mix.

Be sure to check out the rest of our website and blog pages for other information on growing with hydroponics.

See below a step to step guide on how to build a Flood and Drain system.