This is a diagram of an ebb and flow hydroponic system

What Is Ebb And Flow Hydroponics?

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The ebb and flow hydroponic system also called a flood and drain system. This is one of my favorite methods of hydroponics due to its ease of use, capabilities, and reliability. You can customize an ebb and flow system to grow just about any type of plant with great success.

How Does An Ebb And Flow Hydroponic System Work?

The grow tray of an ebb and flow hydroponic system is slowly flooded with nutrient solution. This provides the plants with the nutrients they need. The amount of time it takes for grow tray to fill is controlled by the rate of flow from the reservoir. When the hydroponic solution is then drained when it reaches a certain level or after a set amount of time. As the nutrient solution drains from the grow tray it allows oxygen to the root system. The process is then repeated over again. This constant flooding and draining provide your garden an abundant amount of oxygen and nutrients that promote fast, healthy growth.

Though I typically fill my grow beds with grow medium, plants can also be in individual pots within the grow bed.

Ebb and Flow Hydroponic System

Different Ways Ebb And Flow Systems Can Drain

In ebb and flow systems,  the grow bed is flooded until the nutrient solution reaches a certain level. At that point a standpipe allows water to flow down a drain tube back into the system’s reservoir. The pump can be set up on a timer to run for certain intervals, flooding the grow bed over an extended period of time.  When that time is up the pump stops and water drains back down the pump, draining the grow bed. After a set amount of time, the timer kicks the pump back on and the process is repeated.

Draining the systems automatically involves using a bell,u or loop siphon. Using one of the this “automatic” drains on your ebb and flow system allows you to run your pump 24/7, so there’s no need to use a timer. A loop siphon is a tube that is looped on the outside of the system and leads to the reservoir. When the water completes the loop it creates a vacuum, pulling the water from the grow tray and draining it until the air in the tube cuts the vacuum. Creating a bell to go over the standpipe drain of your system is also a method of creating a vacuum to drain your system. As the water goes down the standpipe and hits an elbow it creates a vacuum draining the system. When water breaks the vacuum, the system fills again.

What Grow Medium Works Best In Ebb And Flow Hydroponic Systems

There are a few different factors that you should consider when choosing a grow medium for your ebb and flow system.

Water retention– Ebb and flow systems work best with grow mediums that retain some moisture but drain well. Lava rock and hydroton clay pebbles both have these characteristics.

If you’re growing root vegetables– Root vegetables will need to be able to push grow medium to form a mass. Hydroton is more suitable for this than lava rock. Other grow medium like a vermiculite/ perlite mix also works well with root vegetables. Remember that you will need a deep grow bed to allow a solid root mass to have room to form.

Weight/ buoyancy- Your grow bed should be strong enough to hold the weight of your grow medium and water. Since your grow bed it being filled with water causing lightweight grow medium to float, disrupting the plant’s root system.

What grow medium I use– I prefer to use expanded clay pebbles in my ebb and flow systems. They are reusable, lightweight, and have good air to water retention. They work well in an ebb and flow hydroponic gardens that have the grow bed filled with grow medium and the systems set up for individual pots.


Ebb and flow hydroponics is an extremely effective hydroponic system for growing plants. It is versatile and customizable making it great for hobby hydroponic gardeners. If you want to learn about other hydroponic methods, check out this article on different hydroponic systems!

5 Answers

  1. Roy Radford
    November 21, 2018 at 4:31 pm

    Thank you for taking the time and trouble to prepare these articles. The flood and drain system you describe is very similar to my own though, being 80 years old, I’m old-fashioned enough to call it gravel sub-irrigation. (As did Dudley Harris more years ago than I care to remember!)

    One small point. Your diagram shows the growth tank being filled by a standpipe ABOVE the medium. As the old name implies, I feed from UNDERNEATH the medium, keeping the top inch or so (2.5 cm if you use these new-fangled Centigrade units! ) dry. This discourages molds and some bugs. Further, the system you show would NOT drain back through the pump, mine does as the feed is from underneath the growth tank.

    1. NoSoilSolutions
      November 22, 2018 at 8:06 pm

      Thanks for stopping by the site Roy! I actually designed this system in particular to be automatically drained with a bell siphon as opposed to using a timer on the pump. I wanted to be able to have the water come over the top so I can easily control the flow rate since bell siphons requiring some tweaking. I enjoy experimenting with the different auto siphons.

    1. NoSoilSolutions
      November 23, 2018 at 11:36 am

      The pipe that runs the water into the systems goes down a few inches below into the grow bed and the standpipe draining the bed starts draining when the water level is still several inches from the top. I really don’t have too many issues with algae or molds.

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