Ebb and Flow System for Hydroponics: What Is It?

Ebb and flow hydroponic systems are inexpensive to design, highly versatile, and a reliable method to irrigate your plants without soil. Also called a flood and drain system, this setup is different than other types because the roots don’t sit standing water. 

The way an ebb and flow system works is a pump moves the nutrient solution to the grow tray to feed and flood the roots. The excess solution drains out and returns to the reservoir. The nutrients recirculate multiple times per day. 

Most hydroponic growers set up ebb and flow systems on a timer. The pump provides a nutrient-rich solution (their food) to grow strong plants in a vertical gardening space. This is a great system for beginners getting started with hydroponics and is relatively easy to DIY.

Ebb and Flow Meaning

Ebb refers the water that is retreating, and flow refers to the incoming water. In hydroponics, it’s an effective system for growing robust plants.

What Is an Ebb and Flow System for Hydroponics?

In hydroponics, ebb and flow is when water flows to the plants, flooding them. Then it retreats. All of the systems work on the basic premise of a grow tray (also called a flood table) filling with water for root nourishment and then draining into a reservoir.

The plants become flooded with the nutrient solution. After the roots take in the nutrients, the excess nutrients are drained back into the reservoir to be reused. Throughout the day, there is movement and recirculation of water. 

You set the fill and drain cycles on a timer so it’s hands-off and easy to maintain.  

Plants are isolated in separate containers just like conventional potted plants. With this system, you can easily add and remove containers with plants without disturbing the surrounding plants. This allows each plants roots to get the nutrients they need. You can also grow a wide variety of plants.

Although it sounds relatively simple, there are materials and hydroponics equipment needed to make an ebb and flow system work. The good news is you can do it yourself, and most are one-time purchases. 

The plants grow in inert media such as Rockwool, perlite, and/or coco coir. Unlike with growing in soil, these growing mediums don’t contain any nourishment for the plants. However, they keep the roots in place and help anchor and support the plants. 

Hydroponic Ebb and Flow System DIY Components

Before buying anything, consider where you will set up your ebb and flow system. How much space do you have? Will you set it up outdoors on a patio, indoors in a greenhouse, or somewhere else? You will need access to an electrical outlet in order to run the pump. Consider also if you will be using grow lights.

We recommend buying materials you need to set up the system first. These include the “hardware” so to speak. Then come back when you are ready and buy the nutrient solution, the aggregates, pots, and plants. Keep in mind, you can buy an ebb and flow hydroponics kit or DIY the system yourself.

There are several things you need to build a DIY ebb and flow system. The goal is to bring nutrient solution into the grow tray and back down the reservoir beneath. A few of the essential components to building an ebb and flow system include:

  1. Plant trays
  2. Watertight fittings
  3. Tray stand
  4. Plant pots
  5. Reservoir – with a cover is recommended
  6. Timer and submersible pump
  7. Nutrient-rich solution
  8. Growing medium or aggregate
  9. Grow lights – optional
  10. Air pump and air stone
  11. Monitor for pH, temperature and conductivity – recommended but may need to buy later, depending on your budget

1. Grow Tray, Flood Tray or Plant Tray

The flood tray you choose is important and are integral to a seamless setup. Consider the size as the larger they are, the more you can grow. You’ll use the tray to hold your plants inside their pots, so it will need to be decently-sized. The flood tray’s responsibility is to allow the nutrient-enriched water to flow through the bottom of the plant pots.

We recommend going to a local gardening center or nursery — instead of a home improvement store such as Home Depot or Lowe’s — to get the plastic grow tray. This is because it will be better suited for hydroponics gardening with ebb and flow. You should choose one designed for hydroponic growing. 

You want to be sure the plastic growing tray has high sides. Look for trays that are a minimum of 6 – 7 inches in height. They need to be high enough so you can flood the roots effectively.

Another feature to look for is that the growing tray has ridges at the bottom. Ridges will help any runoff nutrient solution to be channeled away and recirculated. With flat bottomed trays, plants’ roots can suffer from pooling.

As the nutrients reach your plants’ roots, they will quickly be absorbed as the water runs through them. During this phase, the roots are starved of oxygen.

The opposite end of the flood tray will then filter back into the reservoir, where the remaining nutrients can be repurposed. During the draining process, the roots will be oxygenated, allowing them to absorb the nutrients quickly.

Ebb & flow hydroponic systems
Ebb & flow hydroponic systems

Drilling the Holes

With most any grow tray you buy, you will have to drill your own holes on the bottom.

  • You will need two holes. One hole to allow the pump bring nutrient solution into the tray and the another hole is for the overflow so the solution can drain out (so you don’t flood everything).
  • Position both holes at the lowest point of the tray. 

2. Watertight Fittings

You will need watertight fittings. These are available as an ebb & flow fitting kit. Whatever fittings you buy should come with two gaskets to ensure a water tight seal. 

3. Tray Stand

The tray stand is important because it will raise your plants up a couple of feet allowing you to fit a reservoir neatly underneath. It will also be helpful so you can tend to your plants without having to bend down. Another purpose is it keeps plants high enough so small pests (and pets!) can’t access them.

You can purchase tray stands designed for ebb and flow systems. You can also DIY your own. It will need to be sturdy enough to hold the weight of the grow tray with the plants and substrate, including the increased weight of the flooding. 

4. Plant Pots

Instead of planting your vegetables, herbs, or fruit directly into the soil, this method requires pots. You’ll need to fill the pots with a type of inert growing media, such as Perlite, and then plant the seedlings.

ebb & flow
ebb & flow

Consider the size of the plants you will be growing. For heavy-fruit producing annuals, you will want pots that are 3 – 5 gallons large to accommodate the plant and maximize its growth.

5. Reservoir

The reservoir is one of the most critical components of your ebb & flow system. In this component, you will store your nutrient-dense water, and it will be located directly below the plant or flood tray. 

We highly recommend you set up a reservoir with a lid. With a lid there will be less evaporation as well as fewer algae issues. Another benefit is that because the reservoir is on the ground — on a porch or patio — there will be less chance of critters disturbing it.

Consider that you should have a minimum of 30 gallons of nutrient solution for each 8 square feet of grow tray. 

An overflow tube sets the water level height in the flood and drain system. It will also ensure the nutrient solution doesn’t overflow. You will also want to make sure there are fill and drain tubes to allow water to move seamlessly for nutrient flow.

Using a reservoir with this system is ideal for water conservation and ensuring no nutrients go to waste.

Depending on the number of plants you have and contaminants, you should reuse the same water for up to a week. Whenever you change the water, you will add more nutrients to ensure it still nourishes your plants.

6. Timers and Pumps

Timers and pumps are essential to your ebb and flow system’s success because they make sure the plants are fed with the fill and drain cycles. The timer tells the system when it’s time to fill the flood tray and drain the flood tray depending on your plant’s needs. In this way, you can establish a general hydroponics feeding schedule.’

The nutrient solution is pumped up into the grow tray until it reaches the overflow. You can adjust the height by adding extra blocks. At this point the pump should switch off and the nutrient solution drains back into the reservoir through the pump itself. It will be essential that all of the nutrient solution drains back into the reservoir so that your plants won’t be left sitting in puddles.

Again, it’s important to have growing trays with high sides so you don’t flood the surrounding area.

The submersible pump is responsible for controlling the length and frequency of the watering. You will be able to determine the frequency and how many gallons by the size of the grow tray, the volume of the plant roots, and the growing substrates. 

How Often Should You Flood?

When deciding how often to flood the roots using an ebb and flow system, you need to consider the following:

Absorbency of the growing media

  • Clay pebbles flood 4 – 10 times per day
  • Rockwool cubes flood 1 – 2 times/day
  • 50/50 mix of coco coir and perlite flood 1 – 3 times/day

Size and material of the pots

  • Fabric pots are ideal for ebb and flow systems

Size of the plants

  • Larger plants drink more. You will need to increase the frequency and/or volume of nutrient solution as the plants grow.

Choosing a Pump for Ebb & Flow System

You need a pump that can handle the volume and frequency of pumping the nutrients to the plants. To calculate the volume of nutrient solution, you need to:

  1. Calculate the square footage of the growing tray
  2. Add 25% to it (to account for the roots and growing medium)
  3. Multiply by 10 to get the number of gallons

Choose a pump that can handle at least that many gallons per hour. As an example, if you have a 2 foot by 4 foot grow tray equaling 8 square feet, the pump would need to be able to accommodate a minimum of 100 gallons per hour.

Ebb and flow system reservoir pump
Ebb and flow system reservoir pump

We also suggest using filters on your inflow and overflows. These come standard in the fittings kits. Using filters will help capture and prevent any extra bits of growing media or other particulates from clogging the system. 

Choosing a Timer for Ebb & Flow System

It is best to control your pump with a digital timer. It should have an on/off switch along with the ability to set it by the week, hour, minute with a programmable clock. We like the Titan Controls Apollo 9 2-Outlet Digital Timer, model 734105. It’s easy to use and reliable.

A digital timer will allow you to time the floods precisely so the plants won’t be sitting in nutrient solution for any longer than they need to.

In general, flooding should not be longer than 5 minutes. Segmental timers only work in 15 minute periods which is too long. As soon as you see nutrient solution flowing back into the reservoir via the overflow, the pump should be switched off. 

7. Nutrient-Rich Solution

The nutrient-enriched solution is what provides your plants with the necessary components for healthy growth. The best hydroponic nutrients will include a combination minerals such as phosphorus, nitrogen, potassium, and calcium in the solution. You dissolve the nutrient solution in water which then goes through the system to feed your plants

8. Growing Medium aka Substrates

Because you won’t be growing in soil, you will need to provide an inert growing medium for your ebb and flow hydroponic system. The substrates you choose won’t provide nutrients to your plants. However, they help to anchor the roots and support the plants, especially heavily fruiting annuals.

Fortunately, the ebb and flow system setup works well with many different mediums, allowing you to choose your favorite. Coconut coir, which people also call coco coir, is an incredibly popular growing medium for most all types of hydroponics. Try mixing 30 – 50% perlite with coco coir when growing with ebb and flow.

Other substrates to consider using with the flood and drain system are expanded clay balls, Rockwool, sand, and gravel. 

9. Grow Lights

Depending on where you live and the amount of natural light your hydroponic-growing plants will receive, you may want to consider LED grow lights. There are grow lights that are better for indoors as well. Again, these are optional, depending on your situation. However, you should plan for them when you decide on the space you will set up the ebb and flow system.

10. Air Pump and Air Stone

Aerating the nutrient solution with and air stone and air pump can help to increase dissolved oxygen levels.

11. Monitor for pH, Conductivity and Nutrient Temperature

Having an electrical monitor that connects to the computer can send you reports so you can monitor what is happening and adjust accordingly. This also takes the hassle out of measuring pH levels and the temperature yourself which will save you time. It is worth investing in this.

We recommend BlueLab Guardian Monitor Connect. It may not be something you have the budget for in the beginning; however, as you grow and decide to stick with the ebb and flow system, you may want to consider purchasing. 

 

How Do You Do Ebb and Flow Hydroponics?

An ebb and flow hydroponics system isn’t the simplest type, especially when compared to wick systems. However, with a basic understanding of hydroponics, it’s a great way to upgrade your system. Compared to smaller systems, you can start to work with more advanced plants for a more diverse garden.

Types of Ebb and Flow Systems

Before building your hydroponic garden system, you’ll first want to consider the two main types of setups you can use.

Flooding Tray Setup

This is the setup we recommend. With the flooding tray design, there is an extensive list of ways you can design the setup. It’s an excellent option for hobby farmers who want to use a single container for growing plants. Your tray will sit on top of a raised surface with the reservoir located beneath the plant tray.

As water floods the tray from the reservoir using one tube, the other allows water to move from the container to the tank. All of your plants will need to be placed inside of pots or a plastic bucket in the flooding tray filled with growing media.

Ebb and flow growing tray
Ebb and flow growing tray

You will also want to make sure there’s an overflow tube that allows you to manage the water’s level in the tray. You’ll find this type of ebb and flow system is the most recognizable and the easiest to maintain. Also, transporting your plants is far more straightforward with this technique than other types of hydroponics.

Containers in Series Setup

With this particular design, you’ll need to spend more time setting it up, but it can take up far less space. Using containers in series, you can connect as many plants as possible, allowing you to create a very diverse garden.

Most of these designs have multiple buckets connected using a single tube. The tube is responsible for making sure the nutrient-rich solution reaches all of the buckets evenly.

After the individual containers have been thoroughly watered, the remaining solution is drained back into the reservoir using the same tube. What makes this setup different from flooding trays is the number of containers you’ll have connected.

However, there are plenty of similar characteristics, such as the need for an overflow tube for managing your water level. Containers and series can also be less expensive, depending on the number of plants you have.

This process requires gravity more than pumps to ensure the water drains to save on added costs. Learn about building DIY hydroponic systems.

 

Tips for Maintaining Ebb and Flow System

Maintaining your ebb and flow system is equally as important as making sure it’s built correctly. Using these tips, you should master the art of producing high yields while ensuring your plant’s health.

Managing Timers

The timers in your system are essential to remember, as they control the entire system. Your timers will alert the pumps to push nutrient-rich water to your plants and drain the water, so your plants don’t drown.

Improperly managed timers could lead to roots drying out or plants drowning, destroying your investment. Ideally, find a timer with five-minute intervals, allowing you to soak the growing medium for the perfect amount of time.

Checking pH

The pH level of your water is essential regardless of the type of DIY hydroponics setup you build. You will want to take the health of your plants and the inert growing medium into account. If your water has too low or high of a pH, the plants won’t absorb the nutrients.

You will also want to consider the natural response your plants have during their growth phases. It’s common to notice an increase in pH as your plants get healthier. Unfortunately, it could also be a sign of improper water temperature or algae growth.

For most plants, a pH around six is ideal, but it’s crucial to confirm the independent needs of the plants you own. You can opt to buy a monitor which will automatically measure pH.

Top Watering Plants

You might be wondering, why would I need to topwater my plants in an ebb and flow system? Little do many know that top watering helps to push nutrients through the entirety of your plants.

You will also want to top-water in the beginning when the plants roots are small. Until the plants are sufficiently established in their pots, the roots may not get wet. You should manually top feed at the beginning of their growth cycle.

However, you will not want to use plain tap water for top watering, as it will shock them. Instead, use some of the nutrient-dense water from the reservoir for top watering once per week.

Nutrient Solution Maintenance

The beauty of growing with hydroponics vs soil is you can control the environment. This means you will need to monitor the temperature of the nutrient solution. Ideally, it should be in the 66 – 73 degree range. If they are warmer, you can get a larger reservoir or a nutrient chiller. A monitor can measure the temperature (as well as pH).

In addition, as water evaporates and as the solution is pumped through the system, the nutrient solution can become more and more concentrated. To avoid this, you can top off the reservoir with plain tap water or rainwater. This is something you will have to play around with because a lot depends on your climate (arid, humid, etc.). Plants require more water than minerals.

Also, as a general rule, you should completely change out the nutrient solution every 3 – 4 weeks. 

Cleaning

Cleaning is one of the most critical maintenance procedures, especially since you should do it before setting up your system. Using a 10% bleach solution, you should clean the plant box before adding your plants to ensure there aren’t any contaminants.

You will also want to ensure you remove dead leaves because they can bring fungus gnats. As with any other type of garden, removing diseased plants is of the utmost importance.

Considering ebb and flow systems push the same water through all of your plants, you won’t want cross-contamination. Consider also any standing water or stagnant water which can create pythium growth. This is a water mold responsible for root rot.Ebb and Flow System

How Often Should I Flood My Ebb and Flow?

Flooding is a highly important thing to consider with the hydroponic ebb and flow system, but it’s not a one-size-fits-all approach. Deciding how often to flood your setup depends on your plant’s needs and the type of growing media you use.

For example, Hydroton pebbles don’t have a large water holding capacity; you’ll need flooding every two hours for 15 minutes. We don’t recommend these for an ebb and flow system as ideally you will flood the tray for a maximum of 5 minutes. However, if you use a mix of perlite and coco coir, you can flood 1 – 3 times a day. With Rockwood, you may need to flood just 1 – 2 times per day. 

A few other essential factors to consider when developing a flooding schedule include:

  • Plant size
  • Type of plants
  • Size of the system
  • Nutrient solution
  • Humidity
  • Temperature
  • Light

You can use some of these broad guidelines to help you get started with designing a reliable schedule for flooding.

What is the Best Grow Medium for Ebb and Flow?

One of the best grow medium for ebb & flow is rockwool. It’s porous and also absorbs well. 

Rockwool

  • You can flood up to five times per day
  • Flood a minimum of one time daily
  • Flooding should occur nor more frequently than every three hours

While rockwool is the best, using coconut coir or clay pebbles will also work.

Coconut Coir

  • You can flood up to five times per day
  • Flood a minimum for three times daily
  • Flooding should occur every three to five hours

Clay Pebbles

  • You can flood up to eight times per day
  • Flood a minimum of four times daily
  • Flooding should occur every two to four hours

Difference Between Ebb n Flow and Other Systems

When comparing ebb and flow hydroponics setup to other popular methods to other types of hydroponics, here are some of the major differences. 

Ebb and Flow: The water pump system floods the roots and then drains the nutrient-rich solution to be used again. This is also called a flood and drain system.

Deep Water Culture (DWC): Roots are always in a nutrient solution while oxygen is supplied through air pumps. The system doesn’t drain like it does with an ebb & flow system.

Nutrient Film Technique (NFT): The nutrient based water is constantly running through the system. Requires an air pump.

Wick Technique: This differs from the ebb and flow system because the wicks transfer the hydroponic nutrients to the plants.

Advantages to Using Ebb and Flow Hydroponics System

Ebb and Flow systems are popular because they are not as space-intensive as some other types of hydroponic systems. This type of system is also great for beginners who want to start growing plants.

There are a few advantages of using an ebb and flow system including:

  • Space-efficiency – the nutrients are in the reservoir underneath the grow bed
  • Ease of use
  • Versatility in the types of plants that can be grown
  • Uses less water than other types of hydroponic systems
  • Used in any climate
  • Efficient at delivering nutrients to plants
  • Passive system; doesn’t require a lot of hands-on time and maintenance

Is an Ebb and Flow System Worth It?

An ebb and flow system, also known as flood and drain, is a hydroponics setup to consider. It’s ideal for growing small and medium-size plants. Flooding the plants’ roots is an effective method of irrigation.

During the flooding phase, the plants’ roots are feed with nutrients. In the draining phase between flooding, the roots absorb oxygen they need to grow. Because it’s set up on a timer, it is low maintenance.  

The nutrients recirculate which drives out all the stale oxygen-depleted air from around the plant roots. When the nutrient solution drains back into the reservoir, fresh air is drawn which encourages healthy roots. It also helps to wash away any excess salts.

Ebb and flow consistently produces larger yields than hand watering soil gardens. Plants benefit from the routine that pumps and timers provide. It’s an ideal method for many fruits and vegetables, and you may have high yields in less time than with other hydroponics systems.

Hydroponics is a significant improvement in the sustainability of the future. Gardening this way enables you to use less water and grow more in less space. You control the nutrient solution and the lighting as well.

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