6 Types Of Hydroponic Systems
As you might probably know, hydroponics is the method of growing plants without soil
by supplying them with a constant nutrient solution. Despite the fact that this method remains fairly unknown outside of a small sector of the horticultural world it has
in fact been around for a long time and here I intend to explain the most common types of the system.
Although there is a great deal of variety in the different types of #hydroponic systems, in essence, it comes down to six different types. The drip system, the #ebb and flow system, N.F.T., the #water culture system, #aeroponics and the #wick system. These systems can all be modified to suit the environment and budget of the individual user and the space they have available to them. In choosing an appropriate system for your own needs you need to
consider these things as well as the size and types of plant you will be growing. Remember also that systems will need to be cleaned very thoroughly from time to time so look for a unit that you can disassemble and clean easily.
The Drip System:
This is one of the most popular systems both for the home gardener and the commercial producer. One of the main reasons that it is so popular is that it facilitates the production of large plants. Basically, each plant is potted into growing medium in an individual pot. A drip line is then extended from the reservoir to each pot and when the pump is turned on nutrient solution drips into the pots until such time as the medium is soaked through.
The excess solution then drains through the pot to where it is captured in a tray which returns it to the reservoir by means of gravity. The timer is set to turn the pump on again just before the medium gets dry so that the roots are kept constantly moist. In domestic units, these systems tend to be circulating but some commercial units are non-circulating. What happens in these larger operations is that when the water drains through the growing medium it is not captured. This may sound wasteful but it relies on the fact that the timer is so accurate that when setting correctly it gives enough solution to the growing medium to wet it exactly with very little waste. Just before the medium dries it then adds more solution.
The advantage to the commercial grower is twofold. Firstly, he is not required to have a huge area of catchment trays running the solution back to the reservoir and secondly each time he tops up the reservoir he can replace the exact amount of nutrient appropriate to the plants’ needs. The nutrients within a system decrease as they are absorbed by the plant and so a circulating system must be checked frequently to measure the nutrient levels. In a non-circulating system the reservoir must be topped up frequently but on large scale operations, there is normally staff in place to see to this.
Ebb And Flow System:
This is a method that suits the smaller scale of the domestic user either in the house or in the garden because it is easy to build and can be designed to fit into any available space. Plants are potted into a growing medium and placed into a fairly deep tray. An overflow line is
connected to the tray at a level of one or two inches below the surface of the growing medium and water is then pumped from the reservoir into the tray. When the water
level reaches the overflow it simply runs back to the reservoir. When this starts a float valve turns off the pump. The same valve turns the water back on again when the reservoir refills.
In this way, the roots of the plant are constantly being submerged in solution and drained again. It is a system that can be made on a really tiny scale and many pre-made systems utilize this method. When building your own system be sure that the overflow pipe is sufficiently large to carry away water faster than it can arrive via the pump.
Nutrient Film Technique:
In this system, plants are grown in a matt of material such as rock wool and placed into a tray with a fine film at its base. A pump carries the nutrients through the film and this soaks the film keeping the roots constantly damp. Excess water simply runs back to the reservoir via gravity. Plants are normally planted through some sort of material to keep light from reaching the roots as there is no growing medium to cover them.
The system can be very small but when used on large scale operations long channels are filled with film and the same system is just notched up to a greater size. Because of the shallow depth of this system, it is most suited to small fast-growing crops such as lettuce and certain types of herb. The system is very effective but with small fast growing plants of this nature, there is a risk of them dying quickly in the event of the roots drying out so there is little time to respond if there is some sort of breakdown in the system such as electrical failure.
Water Culture System:
In this system, the root is constantly kept wet by the very fine splashing of tiny droplets of nutrient mix. The plants in are suspended with their roots hanging down into the reservoir. Instead of a water pump, an air pump is placed into the reservoir and the water aerated at a pressure that will make the water look like it is boiling lightly. Because the top of the roots is just above the nutrient mix level the bubbling effect created by the pump will cause droplets to hit the roots.
This system can be as simple as a large plastic bucket with a hole or holes cut into the lid through which the roots are suspended. The air pump is then placed in the bottom of the bucket and the lid put back on. (You may need to cut a groove for the lead to the pump). The most difficult part of the operation is setting the water depth so that it adequately splashes the roots. Don’t worry if the lower roots touch the solution as long as there is still plenty of root material exposed to the air. Make sure that the lid is made of a material that will keep the roots in the dark. This method ensures a really well-oxygenated mix reaching the roots but it also requires monitoring of the depth of the solution. More sophisticated systems of the water culture system are used commercially but at the same time, it is just an upgrade of the system used by the Aztecs that I mentioned at the beginning of this book.
Another variation of the #hydroponic system is called aeroponics but as you will see the main principals differ very little from the other techniques you have seen so far. Once again the plants are supported above the solution supply only this time the solution is mist sprayed onto the roots. Like with NFT, no growing medium is needed. Think of those small fine sprays you have on an ordinary garden irrigation system.
The nutrient solution is pumped from the reservoir and instead of going directly to the router it passes through the sprayers which wet the roots with a fine mist of water. Excess water can then be captured in trays and run back to the reservoir although the spray spreads the water further and so recapturing the nutrient
solution is harder. Most commercial units don’t attempt to recapture the moisture but instead, try to regulate the delivery system so precisely that there is minimal waste.
The Wick System:
Of all the systems that have been discussed so far, this is by far the simplest one. The plants being grown are potted in their growing medium and then suspended above a bucket of nutrient mix. At its most basic you could have a plastic container with a plant inside balanced on a bucket of nutrients. A wicking material is then placed between the growing medium and the nutrient mix. This can be any material that will carry moisture such as a hemp rope, strips of carpet underfelt or some twisted strips of hessian sacking. There are no moving parts, material costs are minimal if any, and there is a very little skill needed to put it all together. There are however multiple problems with this method.
Firstly only small plants should be grown as the wick, even if you use several, will not be able to carry sufficient water to satisfy the needs of a larger plant.
Secondly, the wick will not transport the nutrients evenly and those left behind in the reservoir will build up to form a residue that could become toxic to the plant.
Thirdly there is no oxygenation taking place in the reservoir. This means could be used by a beginner to grow a few small plants as an introduction to other systems of hydroponics. It is also often used by teachers as a means to demonstrate capillary action as that is what is taking place here. Some people use an L shaped tube to carry water to the bottom of a plant’s roots.
When the water is poured down the pipe it will be carried upwards by capillary action in the growing medium but this is not really hydroponics in its true sense as devised by Dr. William Gerricke. There is another system called aquaponics which is often confused with hydroponics and does, in fact, have many similarities but it is not regarded as true hydroponics. Aquaponics principals involve using the waste matter created by fish to feed plants with a system very similar to those of hydroponics. Adding nutrients in controlled quantities is so essential to the philosophy behind hydroponics that the two subjects are best considered separately.
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