Ebb and Flow (aka Flood and Drain) systems

How it works

Buckets, pots, flood trays, or almost any other type of water tight containers are filled with a grow media such as gravel, expanded clay pellets etc. These do not function like soil or add nutrition to the plants but will anchor the roots and will function as a temporary reserve of water and nutrients.

The system work by simply flooding the plants root system with nutrient solution periodically rather than continuously, (about four to six times a day for short periods of time like 5 to 15 minutes) and is allowed to drain in between flood cycles.

1.The flooding starts when a timer turns on a pump, and water (nutrient solution) is pumped through tubing from the reservoir up into the main part of the system using a submersible fountain/pond pump. The nutrient solution continues to fill (flood) the system until it reaches the height of the preset overflow tube so that it soaks the plants roots. The overflow tube should be set to about 2 inches below the top of the growing media.

2.When the water filling/flooding the system reaches the overflow tube height, it drains back down to the reservoir where it will recirculate back through the system again in the future. The overflow tube sets the water level height in the flood and drain system, as well as makes sure the water (nutrient solution) doesn't spill out the top of the system while the pump is on. When the pump shuts off, the rest of the water siphons back down into the reservoir through the pump by gravity (the main water reservoir is placed below the flood tray) draining the system.

What you need to build a basic Flood and Drain (Ebb and Flow) system

• Container(s) (buckets, pots, trays etc) for the plant's roots to grow in.
• A container (reservoir) to hold the nutrient solution.
• Growing medium of some kind (especially expanded clay pellets).
• Submersible fountain/pond pump(s).
• Tubing and connectors to run from the pump in the reservoir to the system to be flooded.
• A timer to turn the pump on and off.
• Overflow tube(s) set to the height that the water level should reach in the container(s).
• Optimally, an aeration system (air stones etc) should be added at the very bottom of the containers. It will increase the plants growth rate and make plants healthier, since pathogens in the container are eliminated by a constant supply of oxygen in both the flood and the drain stages. This is even more important in ebb and flow systems since contamination of the whole system is easy.

Here is some tested solutions

After tests performed on systems in which drainage is by natural flow into the main tank from the containers by gravity has been observed to become impractical for indoor cultivation as they assume that the tank is located at a lower level than the containers. cultivation, either below the floor or at floor level but with the cultivation containers in an elevated position using supports.

In addition to the cost and space they occupy, these supports elevate the plants too much so that they are placed too close to the photosynthesis lamps and the roof of the crop tent (if used).

For medium-sized crops it is recommended to use a central tank of at least 200L that feeds an even number of containers (+ the brain bucket) with expanded clay substrate. Empirically, we have found that the best yields are achieved in systems consisting of 12 or 24 or 48 containers and automation of flood and drainage cycles.

So if you are interested in making the best use of your space for hydroponic applications such as ebb & flow, contact us to design the system that best suits your needs and budget. Of course, we also have complete, tested kits that contain everything you will need to set up the system in your space.