Ebb and Flow Hydroponics Systems: Complete Guide


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Ebb and Flow hydroponics systems are the most popular type of hydroponic system in use today. The name “ebb and flow” is a reference to how water is pumped from one container to another, back and forth, which creates an ebb-and-flow action.

There are a number of types of hydroponics systems with varying difficulty levels to set up and run. Ebb and Flow is one of easy to medium difficulty to set up and maintain. 

In this article, I cover everything you need to know about the popular Ebb & Flow technique, including all the parts you need to build your own ebb and flow system. 

What is Ebb and Flow and How Does It Work?  

Ebb and Flow systems are also known as Flood and Drain systems. An ebb and flow system is a method of growing plants hydroponically in which the roots are periodically flooded with nutrient-rich water and then drained.

The two components to an ebb and flow system are the water reservoir, which stores the nutrient water, and the grow tray above it where the plants are. The grow tray acts as a plant tray, growing area for plants, and as a flood tray (flood table), where the water floods to.

The Ebb and Flow process starts when a timer goes off and sets a water pump into action. It pumps water from a central reservoir up to the grow tray above the reservoir. 

This process will normally happen between 4 – 6 times a day, with the roots remaining submerged in the nutrient solution for around 15 minutes. 

When the water filling reaches a certain height of water, usually when it hits the overflow tube, the pump will stop and the water drains back down to the reservoir. 

During these flooding cycles, it’s important to note the oxygen content, since plants need oxygen to grow. The amounts of oxygen also ebb and flow. When the flooding table is filled with water, oxygen is depleted. But when the flood drains, fresh oxygen rushes back to the plants because the tray flood is gone.

Hydroponic Ebb and Flow System

The flood and drain cycle helps to prevent stagnant water that can lead to diseases and stagnant oxygen. There’s a regular flow of water with the periodic flooding.

An ebb-and-flow system can also be used indoors or outdoors depending on your needs; they’re generally more efficient for indoor growing due to their higher oxygen levels. When growing indoors, grow lights are generally used to give the plants light for healthy growth.

Popular Plants To Grow In Ebb and Flow Systems

One of the benefits of ebb and grow systems is their versatility when it comes to choosing which plants to grow. Here are some of the more popular plants that are commonly grown: 

Leafy Greens

  • Lettuce
  • Kale
  • Spinach
  • Bok Choy
  • Romaine Lettuce

Herbs

  • Cilantro
  • Genovese Basil
  • Thyme
  • Sage
  • Parsley
  • Mint
  • Tarragon

Fruits and Vegetables

  • Strawberries
  • Chilies
  • Bell Peppers
  • Zucchini
  • Tomatoes
  • Cherry Tomatoes

Ebb and Flow Methods

Just as there are different hydroponic solutions to growing plants, there are different Ebb and Flow methods. There are four main varieties of flood and draining to consider.

Flooding Tray Design

This is the most basic and simple type of flood and drain where the plants sit on a grow tray above the reservoir.

It’s the same general method as described above with the constant flooding and draining cycles. Once the flood hits the water limit from the preset overflow tube, simple gravity takes over to drain the flood tray. 

The plants are placed in a holding container, this could be a net pot, basket, or standard potted plants. Normally, these use a growing medium such as Rockwool or coconut husks in place of soil. 

These are ideal systems for germinating and nurturing seedlings and young plants, before moving them to a larger system. The advantage here is the easy movement of plants from one area to another.

Growing different types of plants together can be easier, because you can move them around to accommodate different growth patterns. Strong plants can be put together, medium size plants can be put together, etc. 

This method is also a great indoor system for the hobby grower for its simplicity. The next few design methods are more complicated.

This is a great look at the Flood Tray method of Ebb and Flow systems:

Ebb and Flow Hydroponics Explained!

Plant Containers in Series System

This series design system is used when there are multiple connected plant containers being flooded at the same time.

The series of containers with plants are linked using plastic piping which ensures that each container is flooded during the “Flow Cycle.”

As with the flooding tray technique, the reservoir is situated below the containers, and the water is pumped up to them. The pumps flood with nutrients to a standard water level height for all the containers. 

It’s able to keep the same water height by using a single overflow tube for all the containers. If there were separate overflow tubes for each container, it’d be difficult to maintain the same water height and plant growth. 

Surge Tank Ebb and Flow System

The Surge Tank Flood and Drain system operates by pumping the nutrient-enriched water from the main reservoir to an intermediate “Surge tank” before it goes to the plant buckets/containers.

Unlike in other ebb and flow systems where the reservoir is placed below the containers, the Surge tank is located at the same height as the plants. This system requires more equipment and materials to help the drain movement of water after the flood.

The hydroponic flood won’t flow back to the reservoir through gravity anymore and needs the extra hand. 

This system also uses separate growing containers. The containers and the Surge Tank are connected through tubing and rely on the principle that water will always find its own level to ensure that when the Surge Tank is full the containers are at the same level.

A float valve in the Surge Tank triggers a pump in the tank to start pumping water back to the main tank. Initially, this pump and the main tank pump operate in unison.

After a short while, the timer in the main reservoir will shut the main pump off and the pump in the Surge Tank continues to pump the solution back to the main reservoir until another float valve switches it off when the water reaches a preset level.

Dutch Bucket

This is very similar to the “Series Method” in that the plants are placed in separate buckets. These buckets are all then drip-fed from a central reservoir with each bucket having its own return pipe.

In dutch bucket systems, the water pump can be left to run for 24hrs a day, with the gravity return system on each bucket ensuring the correct water level is maintained. 

Aeration in Ebb and Flow Systems

Ensuring the plants don’t drown is a crucial factor in any hydroponic system. The design of ebb and flow systems is naturally good at ensuring that the roots are exposed to the air for long periods. However, some gardeners still use air pumps to add extra oxygen to the water. 

Most systems rely on the simple mechanics of the system to ensure the roots always receive ample oxygen. Air that has been deoxygenated by the plants is displaced each flood cycle, and as the water ebbs, fresh air is back drawn into the root system. 

Ebb and Flow Advantages

Different types of flood and drain methods will give different advantages and disadvantages, but these are the key points. Let’s first look at some of the main advantages of using ebb and flow.

Easy to Operate

Although these systems can be time-consuming and tricky to set up, once they are up and running they are very straightforward to operate and maintain. 

Most of the maintenance is in checking nutrient levels and the water quality, pH levels and nutrient ratios. 

Simple Structure

The mechanical parts of these systems can be easily and cheaply purchased. This means for someone just getting started, a visit to Amazon.com or a local hardware store to purchase a few key components is all that’s needed to get started. 

Crop Yields

As with all hydroponic systems, key advantages are the speed of plant growth and the improved yields of the crops. When compared to traditional soil-based techniques, ebb and flow systems offer higher yields of between 30% and 40%.

Environmentally friendly

Water usage in these systems is around 90% less than using traditional methods. The plants are also less prone to pest infestations, which means a lot fewer insecticides and chemicals are used in ebb and flow systems.  

Low Cost

Hydroponic grow systems can be built with readily available components. I’ll get more into the various parts below, but they’re not expensive either. You can put together a simple home setup for less than $200 all the way up to a few hundred depending on the size and quality you want. 

Ebb and Flow Disadvantages

Equipment Failure

Unlike passive systems, Ebb and Flow systems rely on the water pumps actively working to continually nourish the plants. If the pump fails or is there is a prolonged power failure, then the plants will suffer. 

Nutrient Levels and Water Quality

This is not specific to ebb and flow systems, but to hydroponics as a whole. Water that is either too rich or too poor in nutrients will quickly affect plant health. It is also essential to monitor pH levels in the water and adjust as required. 

Ebb and Flow Feeding Plants Nutrients

The nutrients are added, according to manufacturers instructions, directly to the main reservoir. This ensures that all the plants are fed constantly, with the exact amount of nutrients they require. 

It is essential not to overfeed or underfeed the plants as this can damage or even kill them. It is also important to monitor water levels for excess salts due to a build-up of unused nutrients.

The general rule of thumb is to replace the water in the reservoir with a fresh mix of nutrients and water every 2-3 weeks. As you monitor your system’s pH and nutrient levels, you may notice that you can extend that to 3-4 weeks before you need to change the water, but don’t go beyond to protect healthy plant growth. 

Inbetween water changes, also be sure to add water because plant roots absorb more water than nutrients. That results in a higher ratio of nutrients than water, nutrient-dense water, which will harm the plants. Monitoring nutrient levels will let you know when to add more water. 

The Bluelab Guardian Monitor has been a great time savings as it continuously monitors pH, nutrient, temperature, and conductivity levels. The Bluelab is on the higher end, but if you just want a simpler check for nutrient levels, the Bluelab Pen will do the trick.

How to Build an Ebb and Flow Hydroponic System

This section covers the materials you need to make a simple and expandable ebb and flow system using the dutch bucket technique. 

Dutch Bucket

This can be any decent-sized container that is watertight and you can alter by drilling holes to add drainage tubes to. 

Growing Medium

This is what supports the plants and their root systems. Common types include:

  • Rockwool
  • Gravel
  • Expanded Clay Pellets
  • Perlite
  • Phenolic Foam

Water and Nutrient Solution Reservoir

This is the main reservoir for holding the water and nutrient solution. It is generally placed below the grow bed and tray level, and has a water pump to circulate the water to the plants.

The reservoir can be anything from plastic storage totes to a large bucket. The important thing is to ensure it is large enough to hold the correct amount of water for your setup.

Submersible Water Pump

This is an essential piece that keeps the water cycling through your ebb and flow system. 

It’s important to get a high-quality pump, because if the pump goes down, the plants roots won’t be able to get the nutrients they need. Keeping a backup pump around isn’t such a bad idea either. 

Digital Pump Timer

If you get a water pump with timer, then you don’t need to get a separate one, but you do need to have a timer to schedule the water pumps. 

As with the need for a good pump, the timer is the same thing. If the timer goes down, the pump won’t know when it needs to pump water, so it won’t. 

Plastic Tubing

Finally, you need the tubing that will carry the water to the plants and back to the reservoir. 

Instead of buying all the parts piecemeal, an option is to buy a complete kit like this one from Hydrofarm Active Aqua with 12 buckets: 

Hydrofarm Active Aqua Grow Flow Ebb & GRO 12 Site 2Gal Hydroponic System|...
  • Brand New Active Aqua Grow Flow 2 gal System w/Controller Unit
  • Comes standard with 12 pots (Expandable to 48 pots)
  • Individual pots (modules) allow you to easily move / relocate plants
  • Each controller can control from 6 up to 48 plant sites… plenty of room for expansion
  • A smaller reservoir (55 gallons) can be used with less water compared to flood & drain tables

Last update on 2021-09-22 / Affiliate links / Images from Amazon Product Advertising API

The great thing about these setups is you can mix and match different materials for different budgets if you understand what each part is used for. Using old coolers or ever water bottles aren’t out of the question either. 

Final Thoughts on Ebb and Flow Hydroponics

Ebb and Flow or Flood and Drain? Whichever way you prefer to call it, this hydroponics system has many fans calling it their favorite method. Nutrient Film Technique (NFT) and Deep Water Culture (DWC) are just two of the other methods that also have fans out there.

With DWC systems being the easiest to set up, Ebb and Flow is the next easiest, and then NFT. Look at the other methods and see which one you think works best for you.

Ebb and Flow FAQs Frequently Asked Questions

What is Another Word for Ebb and Flow?

Another word for Ebb and Flow systems is “Flood and Drain” because the system floods the plants with the nutrient-rich water, then the water drains to give the plants air and oxygen. 

How Often Should You Flood and Drain?

How often you should flood and drain depends on a variety of factors, including the type of system you are running, the type of plants you are growing, and the grow medium. On average, most systems will flood and drain between 4 and 8 times a day. For example, if you’re using hydroton clay pebbles, flooding 4 to 8 times per day for 15 min. each is good. 

What is the Best Grow Medium for Ebb and Flow?

The best growing medium for ebb and flow systems is another factor that can be swayed heavily by the type of plant and system you intend to grow and use. Rockwool is a great medium in any hydroponic system, but many ebb and flow gardeners have great success using Hydroton, which are expanded clay pellets.