An ebb and flow system is a common and highly effective aquaponics setup. Also commonly referred to as a flood and drain system, ebb and flow systems are widely used in commercial and personal aquaponics because they offer many benefits, including increased root oxygenation and consistent water circulation. These benefits can improve plant growth, ensure plants are receiving nutrient-rich water from the fish tank, reduce issues associated with water stagnation, and aids in filtering the fish waste from the water, which keeps your fish healthy and happy. To get started with ebb and flow aquaponics, you need to understand what it is and how it works. In addition, I’ll show you how to build your own ebb and flow system, complete with step-by-step pictures in this two part post.
What is an Ebb and Flow System?
An ebb and flow or flood and drain system is one of many types of aquaponics systems. A basic aquaponic setup includes a fish tank or pond for the fish and grows beds for the hydroponic plants. The fish tank requires a means of oxygenating the water and is generally connected to pipes, pumps, and a drain. The grow beds house the plants and are commonly filled with a pH neutral grow media that offers support to the plants and provides additional surface area for bacteria growth. The bacteria in the system are what make the conversion from fish waste to plant food, making them essential to the success of your aquaponics system. When the fish, plants, and beneficial bacteria work in harmony, you have a fully functional and highly-productive aquaponics system.
Flood and drain systems transfer water back and forth between these two pieces, alternating between filling or flooding the plant’s grow beds and completely draining them. This process can be accomplished using pumps, timers, or a bell siphon to control the movement of the water. The nitrogen cycle is what keeps all aquaponics systems working. In an ebb and flow system, the fish produce waste that has a high ammonia level. Nitrifying bacteria then begin the process of converting that ammonia into nitrites and then nitrates. Once the grow beds are flooded, the nitrates are removed from the water by the plants, which use it as food. The end result is clean water that can be returned to the fish.
How Does an Ebb and Flow Aquaponics System Work?
In order for an ebb and flow aquaponics system to work, there must be some means of moving water back and forth between the hydroponic grow beds and the fish tank. The most effective way to move water in and out of the grow beds is the bell siphon method because the bell siphon controls the flood and drain cycle automatically. This means no timers to set, very little maintenance required, and only a small amount of time to routinely check the function of the system once it is up and running. The water continues to cycle through the system on a regular basis, keeping the plants happy. The bell siphon method is so effective and common, that people often refer to ebb and flow systems as bell siphon aquaponics.
The bell siphon works using a combination of hydrostatic pressure and changes in air pressure. This may seem complicated, but it is relatively simple in operation. The bell siphon is comprised of several parts, including a standpipe that determines the top level the water can reach within the grow bed. As nutrient-rich water is pumped into the grow bed, the water level will rise until it reaches the top of the standpipe and begins to overflow into it. At that point, the change in air pressure and the movement of the water creates a vacuum that starts the draining cycle. Water is then sucked out of the grow beds until they are almost entirely drained, at which point the bell siphon sucks air, which stops the process and allows the grow beds to start flooding again.
The bell siphon keeps the water moving efficiently through the system, which is what makes flood and drain aquaponics so good for the plants and the fish. As the bed fills with water, important nutrients and hydration are delivered to the plants. As the beds drain, the action draws oxygen deep into the roots of the plants, which also benefits their growth and overall health. The draining cycle takes the plant-filtered water back to the fish, ensuring their habitat is also a healthy one.
In the next post I will demonstrate “How To Build An Ebb And Flow System“.