Ebb and Flow System | Guide and Information
The ebb and flow system gets its name from the two phases of the tide and is one of the basic types of hydroponic systems known today. The ebb phase is the outgoing phase when the tide drains away from the shore and the flow phase is the incoming phase where the water rises again. As you may have guessed, the ebb and flow hydroponics system also have two phases that it uses to give the plants nutrients.
While the system is novel, it isn't’ used much these days outside of hobby uses. Unfortunately, anything this hydroponic system can do one of the other basic systems can do better.
Like all hydroponic system, ebb and flow hydroponics need a container to store the nutrient solution. In this type of system, it is common for the container to sit below the plants so that gravity can help catch the nutrients during the ebb cycle of the process.
You will want this to be water-tight and light-proof so no excess algae or microorganisms grow inside the container. If you use a recycled system (excess nutrients are combined in the reservoir and used for future cycles) you will be at a higher risk for disease and toxins that will require you to flush out the tank and refill it with a clean nutrient solution.
Pump and Timer
Since this system relies on periodic flooding of the roots of the plants, you will need to connect the pump to the timer that matches the intended frequency. Usually, you want to set it up so that the correct amount of water (keep in mind some of it will drain even with the pump on) submerges the roots of the plants while the pump is on. Keep it on for 5-15 minutes and turn the pump off. As long as the drain is placed at the low point of the growing container gravity will do the work for you and ebb the liquid.
For the ebb and flow system, you will want to use gravel or coarse grain sand for the growing medium. Keep in mind that the growing medium will come in contact with the nutrient solution for five to fifteen minutes at a time and you don’t want something too absorbent or it will negate the ebb and flow process.
The ebb flow hydroponics is a great way to get into the more technical side of hydroponic gardening. It requires sophisticated knowledge of the plants you are growing as well as the frequency and duration for the ebb and flow cycles. This means that it is a great way to extend your knowledge of gardening while learning the technical side of timers and pumps.
The size allows it to support a wide variety of plant types and sizes. There are few components (the reservoir being the largest) and depending on what you are growing you can fit it all in a very small place on a counter or in the garage.
This system also allows for strong aeration of the roots as well as the nutrient solution. Since the roots are left in the open air for much of the time they have ample access to oxygen and other air-based nutrients. In addition, some nutrient solution remains in the growing medium or on the roots during the ebb cycle. It has a high surface area and allows for a lot of aeration of the solution as well.
Lastly, it is pretty quiet to operate since there is only a periodic flow cycle that washes the plant roots. It is great for residential or school applications.
The ebb and flow hydroponic system is pretty inefficient when it comes to water usage. Since it doesn’t control the types of nutrients or allow the plants to self-select the nutrients they want (this is the case with deep water culture where the roots sit directly in the nutrient solution), it can be wasteful. In addition, if you are using a closed system there is a greater chance of disease or toxin buildup where you will need to replace the nutrient solution. An alternative to this is to dispose of all of the excess nutrient solution during the ebb cycle, but this is very wasteful.
It can also take quite a bit of time to zero in on the correct frequency and duration for the ebb and flow cycles. You will need to get it right otherwise the plants will be exposed to the nutrient solution for too long and the roots won’t receive enough oxygen.
There are also a few moving parts that could break and will lead to a failed crop. If the timer or pump malfunction or stop working the plants will not receive the nutrients they need.
Lastly, the maintenance can be quite a bit depending on the size and how many plants you have. It is common for the roots to grow together when using this method and it makes pruning dead plants pretty difficult.
How can I deal with root rot mold that may occur using the ebb and flow technique?
The most common solution is to use a peroxide solution. This will raise the oxygen level in the nutrient solution and clear out the water-borne mold. The increased oxygen levels won’t be harmful to the plants.
What type of plants
grow well with the ebb and flow system?
As opposed to the wick system where small plants are usually ideally, the ebb and flow system can work well with larger plants or for commercial applications. It is even possible to set up a modular system where each large plant has its own container and drain system back to a central reservoir.
The ebb and flow system has fallen out of favor over the last few decades, but it is still a great system for those who want to venture into