Hydroculture & Hydroponics

One of the most important aspects of self-reliance and off-grid living is having the ability to produce your own food. Indoor or greenhouse gardening is particularly advantageous for an off-grid lifestyle for one major reason: food can be grown year-round. Hydroculture, in the broadest sense, refers to the process of growing plants without using soil as a growth medium. Hydroculture is becoming an extremely popular choice among garden hobbyists and off-grid enthusiasts as a food production method, not only for the consistent supply of food, but also for the amount of control that one can have over the growing environment.

There are two main types of hydroculture; hydroponics and aeroponics. Although both methods involve the use of an aqueous solution of (i.e. water mixed with) plant nutrients and essential minerals, hydroponics involves the use of an alternative to soil as a growth medium. Several materials, including rockwool, perlite, gravel, and clay pellets are commonly used as a substrate in place of soil; although many other types of materials can be used.   In this method, solutions must be constantly or regularly (through the use of a timer) circulated over the plant roots to keep them hydrated and provide them with nutrients. Another hydroponic method, deep water culture (DWC) involves using water itself as a substrate by submerging roots directly into the nutrient-rich solution.

Consider some of the advantages and disadvantages to using traditional soil, hydroponic or aeroponic systems before deciding which technique is most suited to your home food production needs:

Hydroponic-Advantages

Hydroponic-Disadvantages

Types of Hydroponic Systems

There are several different types of hydroponic system setups, all of which rely on the same basic principles of water distribution but use very different processes. They include:

(1) Drip System

(2) Ebb & Flow (Flood & Drain) System

(3) Nutrient Film Technique (NFT)

(4) Wick System

(5) Deep Water Culture (DWC) System

 

1. Drip System

The drip system is the most commonly used of all hydroponic systems. As in most hydroponic systems, the water reservoir is separated from the rest of the system by utilizing a container in which excess water (i.e. nutrient solution) is stored. Water (solution) is pumped from the reservoir using a pump, which is controlled by a timer.

Plants are held in a grow tray that has individual containers for each plant and its substrate material. The solution from the reservoir flows through tubes, the openings of which are located at the base of each plant, where an emitter controls the volume of flow to the plant. Because each plant’s tube has its own emitter, the volume of solution can be easily controlled for individual plants by using different emitters.

Excess nutrient solution falls through plant roots to the bottom of the grow tray, and through an overflow drain that leads back to the reservoir. Nutrient concentrations and pH levels must be closely monitored as plants consume and change the water chemistry during the progress of their growth. As in many hydroponic systems, air stones (small devices commonly used to aerate fish tank water) are advisable to use to keep the nutrient solutions oxygenated, a process that is essential for healthy plant growth.

Hydroponic-Drip-System
Hydroponic Drip System

2. Ebb & Flow (Flood & Drain) System

 The ebb & flow system is very similar to the drip system in almost every way, with the exception of how the plants receive their nutrient solution. Instead of each plant having its own solution-delivery tube and emitter, all of the nutrient solution pumped up from the reservoir is delivered directly to the bottom of the grow tray.

The ebb & flow system therefore has one advantage and one disadvantage with respect to the drip system. The advantage is that the system is slightly less complicated to assemble. The disadvantage is that the volume of solution to each plant cannot be customized to individual plants through the use of emitter valves. For that reason the ebb and flow system will work well for a setup which is designed for containing the same type of plant in all containers of the grow tray; whereas a drip system may be ideal if, for example, you want to grow tomatoes and lettuce in the same grow tray (possibly requiring different volumes of water/solution for each plant).

Hydroponic-Ebb-&-Flow
Hydroponic Ebb & Flow (Flood & Drain) System

3. Nutrient Film Technique (NFT)

 The nutrient film technique (NFT) also consists of a system in which plants are contained in individual containers in a grow tray separated from the reservoir. As in the drip system and ebb & flow techniques, the NFT system also operates by pumping water and nutrients from the reservoir tank below into the grow tray above. For the NFT system, however, the grow tray is fixed in a slightly slanted position to facilitate constant flow across the bottom of the tray, creating a thin “film” of nutrient solution that flows over plant roots. The solution drains back into the reservoir, where an air stone is often used to oxygenate the reservoir water. It is important to keep the reservoir solution oxygenated because the NFT system requires far less oversight and maintenance than the drip and ebb & flow techniques.

One disadvantage of the NFT system is that it is much more vulnerable to pump malfunctions and power failures. In these cases one should be prepared to replace pumps quickly or manually supply water to plants until power is restored.

Hydroponic-Nutrient-Film-Technique
Hydroponic Nutrient Film Technique (NFT)

 4. Wick System

 The wick system is widely considered the simplest and most-cost effective type of hydroponic system. Although a reservoir and grow tray are both used (as in the techniques described above), no pump is used to deliver nutrient solution from the reservoir to the grow tray. Instead water and nutrients are “wicked” continuously using a highly absorbent material (often cotton fiber) from the reservoir to the growth medium. Highly absorbent growth mediums such as perlite, vermiculite, and coconut fiber are often used to facilitate additional wicking of nutrient solution to the plant roots. In some cases cotton fiber wicks need not be used at all by simply placing the absorbent growth medium in direct contact with the reservoir solution.

Hydroponic-Wick-System
Hydroponic Wick System

 5. Deep Water Culture (DWC) System

The deep water culture (DWC) system is also an extremely simply system to assemble and maintain. In this system, no separate grow tray is used at all. Although each plant is held in its own individual container, these containers are built into a platform (often Styrofoam) that floats on top of the reservoir, such that plant roots grow downward directly into the nutrient solution. No growth medium is required for plants in a DWC system, which further adds to the cost-effectiveness of this technique. Air stones are essential for oxygenation in this system because the nutrient solution is not circulated between the reservoir and grow tray, as in other hydroponic systems.

IMPORTANT: Because plant roots are submerged at all times using this system, relatively few plants are actually suitable for a deep water culture (DWC) setup. The most commonly grown plants that respond well to a DWC system are water-rich vegetables including lettuce, tomatoes, chard and some peppers.

It is also important to consider that the deep water culture system often requires a great deal of oversight to maintain optimum temperature, pH levels, and nutrient concentrations as these can vary greatly.

Hydroponic-Deep-Water-Culture
Hydroponic Deep Water Culture (DWC) System

Aeroponics

Aeroponics is a slightly different process, in which plant roots are suspended, exposing them to the air. This exposure to air is considered advantageous because it provides roots more access to atmospheric carbon dioxide (CO2) and oxygen, gases that are both vital for plant growth. In an aeroponics system, water and nutrients are delivered to plant roots in the form of misting.

Like many hydroponic systems, individual plants in an aeroponic system are suspended in containers above a reservoir which contains the nutrient solution. Water (nutrient solution) is pumped up from the reservoir through tubes that lead to specialized misting nozzles, which provide hydration and food to the plant roots via the mist that is emitted. Like the drip-system hydroponic technique (explained above), the aeroponic system requires timers to control the emission of solution; however aeroponic systems require more frequent feeding/hydration periods in comparison. Because the flow cycle occurs relatively frequently, and because roots are constantly exposed to air, the aeroponic system does not require the use of an air stone to oxygenate the reservoir solution.

Aeroponic-System-Mist
Aeroponic System

Other Considerations

Although the process of assembling and installing all of the components of a hydroponic or aeroponic system may be fairly time consuming and often require a substantial learning curve for beginners, growing and maintaining plants is relatively simple and straightforward once the system is constructed. In addition to ensuring that water (nutrient solution) is reaching the plants consistently, it is important to regularly measure and balance the pH of the solution, maintain optimum temperature and humidity conditions, and check for pests and fungal growth.

Another important consideration for your hydroponic or aeroponic setup is the type of grow lights to use. Depending on several factors – including type of plants, ideal light spectrum for various stages of plant growth, temperature output, and cost of electricity usage – some types of lighting may be more advantageous than others. Many types of lights are available for purchase including fluorescent lamps, incandescent bulbs, high-pressure (and low-pressure) sodium bulbs, high-intensity discharge (HID) lamps, metal halide (MH), and LED lights. It is important to conduct sufficient research regarding your intended hydroponic/aeroponic results, so that you choose the most appropriate lighting for your setup.

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