Ebb And Flow Hydroponic Systems offer the best way for beginners and veterans to grow outdoor and indoor gardens. With Ebb and Flow Hydroponics, herbs, flowers and vegetables can be successfully grown by anyone.
What is it?
Ebb and Flow or Flood and Drain is a form of hydroponics that is known for its simplicity, reliability of operation, and low initial investment....while providing the advantages of hydroponics. A terrific hydroponic set up for a beginner!!!
Also called 'E&F', it is a system of arranging pots filled with inert media. The media doesn't function like soil by contributing nutrition to the plants. Rather, the medium serves as an anchor for the roots and functions as a temporary reserve of water and nutrients as the hydroponic solution is alternately flooded and allowed to ebb
In its simplest form, there is a tray above a reservoir of nutrient solution. The tray is either filled with growing medium, such as clay granules, and planted directly....or pots of that medium stand in the tray.
At regular intervals, a simple timer turns on a pump to fill the upper tray with nutrient solution. After that, the solution then drains back into the reservoir. (This keeps the medium regularly flushed with nutrients and air.)
Once the upper tray fills past the drain, it begins recirculating the water until the pump is turned off. Then, you guessed it, the water in the upper tray drains back into the reservoir below.
Any hydroponic system plans will rely on fertilized & aerated water which....provides both nutrition and oxygen to a plant's root zone, often involving really sophisticated mechanics. That can be daunting to casual hobbyists!!!
Nutrient solutions must usually be below the temperature at which pathogen growth can begin. But not so cool that root growth is suppressed. Active aeration of the nutrient solution is common, since root systems themselves remove oxygen, creating conditions which also can promote pathogenic bacteria and water borne molds.
The good thing is....an ebb and flow hydroponic system utilizes the fact that the solution is not left in constant contact with the roots of plants. This is a way we avoid the need for oxygenating or chilling of the solution..... Instead, we rely on natural root function to provide passive oxygenation at a high level; which tends to suppress pathogen growth.
What Goes Up, Must Come Down!!
Simplicity is maintained through usage of a single, bidirectional path for the solution. Water flows in, and out of the same tube. When the pump has raised water into the tray briefly submerging the roots, the pump is turned off using a switch - typically a timer. The water flows back down the same tube it was pumped up in...eliminating the need for more than one sealed fitting and reducing overall complexity of the system.
Ebb and Flood systems turn on according to how much water the growing medium can hold. Highly water retentive media can require watering only once a day, while others require twice to as many as six times a day....with each "Flood" stage only lasting a few minutes.
How long it takes to flood the roots is not critical. Therefore, smaller pumps can be purchased, making the method popular with amateur and urban gardeners.
Gravity itself acts as the drain pump. So only one pump is needed.
Aeration of an ebb and flow hydroponic system is an important aspect of its operation. Automatic displacement eliminates air which has been de-oxygenated by the roots as the water rises to its highest flood stage. When the pump turns back off, gravity pulling the water back downward re-exposes the space around the roots to atmospheric pressure, which re-fills the voids in the medium.
The film of water left around the roots during Ebb has a high surface to mass ratio, which means that even as the roots absorb oxygen, its high surface area facilitates re-oxygenation which can sustain the roots as long as their surfaces remain damp. The high oxygen content of water filmed this way suppresses most harmful lifeforms...keeping the root zones disease free.
Root rot is where the outer cells of the roots die, turn brown, and slough off when handled. Need for supplementary oxygenation using air pumps is also eliminated which increases reliability; and reduces complexity.
Ebb and flow hydroponic systems are also quiet. While using less power than other hydroponic systems, they can be used in environments where noise and/or excessive plumbing is not a great idea..... such as residential or classroom applications where space is at a premium.
Ebb and flow hydroponic systems are flexible with few drawbacks. Though typically known for compact growing of plants having smaller stature, it has been used for growing large plants, using buckets ranging in size from 1 to 5 gallons, making use of high volume pumps such as those in large aquariums, decorative fountains, and koi ponds.
There are facets to these systems that present some labor ...usually only in large scale applications, though.
1. The biggest being: management of media between uses....such as washing and sterilization. This can be done by dumping a sterilizing solution, such as hydrogen peroxide or chlorine solution, into the tray. You would have to temporarily plug the drain.
Hand removal of root fragments has to be done as well. Larger containers require transferring the media to a suitable location after sterilization to allow removal of leftover plant material.
2. A second drawback to an ebb and flow hydroponic system is that the roots tend to grow together; meaning removal of harvested or damaged plants can be somewhat problematic in plants having well developed root systems.
Commercial crops harvested at one time are somewhat immune to concerns related to that aspect of the system. But, in the event of disease, the problem can quickly spread, as all the roots share the same flood source.
3. Finally, due to conditions wherein roots sit in undrained water trapped by the body of the roots themselves, some E&F systems are not immune to root rot as a well designed system would be. And in systems where plants are larger than optimal for the system, this can create the need for modifications such as screens or beds of medium sized gravel to prevent standing water.
Tilting the tray is one way to achieve better drain characteristics. In "bucket E&F", this problem can be dealt with in a similar manner, ensuring good drainage through using medium of adequate size and ensuring that drainage of the container between flood cycles is complete.
Hydrogen peroxide is also added to nutrient solutions when there is suspicion that the pythium root rot mold has begun to grow on the roots' surfaces. The oxygen liberated from the hydrogen peroxide is destructive to single celled organisms, and is administered in dosages which vary with the concentration of the peroxide.
Typically, several tablespoons of 3.5% solution per gallon or more is used. The temporary rise of oxygen is only minimally damaging to roots....while killing the water born mold can significantly increase yield or even save a crop's life.
Article above used from Wikipedia under the creativecommonslicenses3.0