Ebb & Flow: How Good Is It for Cannabis?

Cannabis Hydroponics System
December 15, 2020

The popularity of hydroponic setups is no doubt expanding thanks to the abounding benefits it brings to the world of horticulture. The system also comes in different types, providing the market with more options. Ebb and flow, also known as flood and drain or flood table, is one of the most sought-after water-based variety today. And, its effectiveness, efficiency, versatility, and ease of maintenance give even the rest of its kind a good run for their money.

Understanding Ebb & Flow

Unlike other types of hydroponics, an ebb and flow system does not continuously cover the roots of plants with water. Instead, it goes through alternating dry and wet phases, similar to an ocean tide coming in and out of mangroves.

The setup utilizes a “feast and fast” model which develops strong, healthy roots. During the flooding phase, used air is forced out of the roots and the plant guzzles on water. Come draining, the opposite happens – starved for oxygen, it feasts on O₂ as fresh air is sucked in but thirsts for water.

How Ebb and Flow Works

Ebb and Flow has a variety of designs, but the primary mechanism stays the same. The hydroponic media anchor the roots of the plant and act as a temporary reserve of water. For short periods, usually around 5 to 15 minutes, the system is periodically flooded with a nutrient solution.

Deep Water Culture System
Deep Water Culture System

After the set time, the pump will stop supplying water to the grow tray. The nutrient solution then races back into the reservoir through the force of gravity, passing through the same line used to push the water up.

A submerged pump connected to a timer is the mechanism that allows such operation. The timer is set depending on the size of the plants, temperature, and humidity, and the growing medium used. There’s also an overflow drain that keeps the water at optimum levels by pouring out the excess back to the reservoir.

Types of Ebb and Flow

As mentioned, ebb and flow can be constructed in a variety of ways. The design depends on the goal, accessible materials, and available space. Each design functions more or less the same. The main difference, however, would lie on how the nutrient solution is supplied to the plants.

Flooding Tray Design

The flooding tray design is the most common type of ebb and flow system used for cannabis cultivation. It floods a single container, usually a shallow square or rectangular tray, that holds plants in pots or baskets with hydroponic media. The operation is useful for herbage that needs to be moved around a lot or starting weeds that will eventually be placed in a larger container.

Pre-veg Cannabis in Ebb and Flow Flood Tray

As water is pumped from the reservoir through the first tube, all of the floras in the tray will be flooded simultaneously. The other duct, an overflow tube, sets the water height during the flooding phase by reducing excess water. After the flooding phase, the water automatically goes back to the reservoir beneath the tray, and the cycle begins again.

Series Of Container Design

Unlike the flooding tray design, this setup floods several separate containers at the same time. Each one is linked to a series of tubing, with the main pipe connected to the pump in the reservoir. For an even water distribution, all the containers are elevated at the same height.

Instead of possessing a separate overflow for each chamber, there is usually just one overflow tube for the entire system. It connects to the network at the base and is elevated like all other containers. The height of the overflow tube determines the water level for the entire system. When water reaches the tip of the overflow, it spills over and goes back to the repository to be pumped through the system again.

Surge Tank Design

Different from the other designs, this setup does not rely on an overflow drain to get water evenly in all containers. Instead, it uses a primary tank, also called a surge tank, with a dual pump to distribute the nutrient solution proportionately and to drain it back. Also, a timer operates the flooding pump, while a float valve turns on the drain pump once the water gets to the set level.

Unlike the other ebb and flow systems, the reservoir of the surge tank design is not placed underneath the containers. Instead, all the components are typically placed side by side. Such a setup is useful when more vertical space is needed as it can accommodate larger plants. However, it is also more complicated and costlier to build.


Related Article: How to Set Up a Vertical Hydroponic System


Pros & Cons of Using Ebb and Flow

Ebb and flow is considered to be one of the best hydroponic systems today for many reasons. If used correctly, it can enhance the quality and yield of cannabis plants. Having said that, this setup is not fool-proof as it also suffers from a few drawbacks of its own.


  • Reliable. The beauty of this system is its ease of operation as the system mostly works automatically. It only requires minimal supervision and maintenance. All that is left to do is to ensure the availability of nutrient solution and constant checking for any functionality issues. Technical assistance is also rarely needed.
  • Versatile. Modifiable in many ways, the setup can also accommodate different types and sizes of plants. It is also easy to integrate into a balcony, a table, or a growing corner, depending on the space available.
  • Abundant in nutrients. Since the system work on a flood/drain concept, plants are submerged with nutrient-rich water in a timely manner. The arrangement also has a safety mechanism in the form of the overflow drain to ensure that plants do not suffer from cannabis nutrient burn.
  • Easier to control the temperature. Unlike other operations, the temperature of the nutrient-filled water is easier to manage in an ebb and flow system. Because the reservoir is in a separate container from the plants, the proper heat can be maintained using an aquarium heater or chiller. Between 20 to 24°C is the ideal temperature to ensure the roots can respire adequately and to prevent harmful pathogens.
  • Modest. The cost of setting up and maintaining a simple setup is generally affordable. It also makes for a perfect unobtrusive indoor structure as it takes up little space, does not require much energy, and is very quiet.
Advantage Disadvantage Opposite Difference Situation


  • Risk of potential losses. One of the main disadvantages of this system is that if something goes wrong, there is a possibility that it will affect the entire crop. For this reason, although the system is generally reliable, constant monitoring and checking for issues is a must. These include broken pumps, clogged overflow, and contaminated water.
  • Vulnerability to root diseases. If set up incorrectly, this system may lead to a variety of root problems. Poor drainage, as well as nutrient insufficiency and poor maintenance can spell the difference between a good output and a ruined harvest.

Things To Consider

To maximize the efficacy of this hydroponic setup, certain things must be taken into consideration. Here’s a list of the things to take note of to prevent any cases of breakdown and ensure that the setup works correctly.

Grow Medium

There is a wide range of grow media available for an ebb and flow setup. When choosing a suitable medium, there are two main things to consider:

  • Water retention. Ebb and flow setups work best with grow media that retains moisture but drains well. It ensures that sufficient amount of nutrient solution is trapped within the root zone even after draining – but not much that it may invite molds and pathogens. Among the best in this regard are lava rock, rockwool, and hydroton.
  • Density/Buoyancy. Since the container is constantly flooded with water, the medium used should be able to withstand its pressure. A lightweight medium may cause the entire plant to float, disrupting the root system. An alternative is to place the plants in heavier pots.

Flooding Schedule

The number of flooding will depend on the climate or temperature in the location and the grow medium used. Ensuring that the roots get plenty of oxygen between flows is of utmost importance. Besides, making sure that the roots do not dry out too much is also crucial.

Below is a simple guide that can be used to determine the appropriate flooding schedule.

  • Twice per day. Watering two times a day can be used in cooler, more humid environments or if employing a slow draining medium.
  • Three times per day. Warmer environments or if using a fast draining medium is ideal for thrice a day water feast.
  • Four times per day. Only flood four times a day if in a hot, dry environment and if using a fast draining growing medium.

pH levels

Monitoring pH levels is essential to ensure healthy plant growth. Many nutrients are only soluble in a certain pH range. If the nutrient solution goes out of the ideal pH level, it may result in a nutrient lockout. To prevent this from happening, make sure to maintain the pH of the solution between 5.5 and 6.5. PH levels can easily be adjusted with the use specifically designed pH up and down products available in gardening stores.

The Best Ebb & Flow Systems on the Market

While ebb and flow system can be constructed at home, there are also many prefabricated setups available in horticulture stores. Below are some of the best hardware that will help bring cannabis growth to another level.

Viagrow 2’ x 4’ Complete Flood & Drain Kit

Type:     Flooding Tray

The Viagrow Flood and Drain Kit from Atlantis Hydroponics is one of the simplest, yet most efficient ebb and flow setups available today. It offers a complete system that delivers the perfect amount of water, nutrients, and oxygen to the plants, boosting its growth rate. Despite being a smaller setup, it can grow up to 10 plants efficiently in a limited space.

Aside from the flood tray and reservoir, the kit also includes a 50-liter bag of Viastone grow rocks, 15 one-gallon nursery pots, a grounded multipin timer, and a 211 GPH submersible pump.

Flo-n-Gro Ebb & Flow System – 12 Site

Type: Surge Tank

Suitable for bigger plants, the Flo-n-Gro Ebb & Flow system is equipped with a 55-gallon food grade reservoir, 12 4-gallon grow containers, and 12 3-gallon 360-degree mesh aeration inserts. The entire system is controlled by a specialized surge tank, the Flo-n-GroTitan Controls Oceanus 1. Also, the containers can hold up to 125 liters of grow media, enough to cater to medium-sized sativa.

Platinium Ebb & Flow

Type: Flood Tray

The Platinium Ebb & Flow system is the most compact hydroponic system available today. Sitting at the height of only 27.5 cm, it is suitable for growing in restricted spaces. It also guarantees favorable water and air ratio. Moreover, its deep table design makes it ideal for rockwool, pots, or airpots.

FarmTek Ebb & Flow System

Type: Flood Tray

FarmTek’s Ebb & Flow system offers a versatile setup that can be used to grow big in small spaces. Its tray and reservoir are manufactured from durable ABS plastic with built-in UV inhibitors to minimize fading from grow lights. Meanwhile, its tank also features a porthole cover, making monitoring and refilling the nutrient solution easier. The system comes in four sizes, allowing it to accommodate larger scale operations.

Big Boy Ebb & Flow Hydroponic System

HTG Supply Hydroponics System
©HTG Supply

Type: Surge Tank

The Big Boy Ebb & Flow Hydroponic setup is an uncomplicated system with easy to operate control modules. It also comes with its unique RhizoCore bucket lids. These covers have a super-aerated center channel, enabling oxygen and nutrient solutions to flow more freely to the root zone – supercharging plant growth.

Site pot layout can be easily modified to fit the spatial limitations. The initial system comes with six growing buckets, but can easily be expanded to 12 or 18 grow sites.

Ebb & Flow Is The System To Beat

While cannabis is traditionally grown in soil and other soil-based media, current trends see hydroponic setups rapidly taking over the industry. The shift on water-based growing has also initiated a search for the most beneficial framework. In the hunt for such, Ebb and flow systems are clear frontrunners. Its efficiency and reliability make it perfect for beginners and experts alike.

Flowering Cannabis in Ebb and Flow

While this structure offers numerous advantages, its effectiveness will still ultimately depend on how it is handled and maintained. Paired with constant monitoring and proper maintenance, the ebb and flow setup can deliver a bountiful, high-quality yield.