Getting Down the Basics
To start, we need to have a simple understanding of what hydroponic cultivation is all about. In short, hydroponics, or water culture, is the soilless growth of plants. Often times the plants’ root systems are suspended in varying types of media that are then injected or flooded with the nutrient solution.
This is a very important aspect of hydro to understand, because in hydroponic growing one key factor is the air surrounding the roots, not just the constant injections of nutrients and water. Many people forget that although plants breath in carbon dioxide (CO2), the plants’ roots breath in oxygen. As such, hydroponic growing is just as much about supercharging the root systems with oxygen as it is about supplying nutrients and water. Hydroponics offers an advantage in this arena because roots are not smothered underneath a lot of soil and air can easily permeate the mediums used in hydro systems.
The medium that holds the roots and the rest of the plant can be one of any type of sterile materials. Most of these mediums are cheap and easy to find in plnt nurseries, hydro shops or even hardware stores. Clay pebbles, Rockwool and coco-coir are some examples of inexpensive and easy-to-find medium to grow plants in. Soilless mixes that look much like rich outdoor earth soil, but are really peat- or sphagnum-based mixtures, can also work extremely well in certain types of systems.
Easy & Inexpensive Hydro Systems
What follows is a brief overview of today’s most popular hydroponic grow systems currently on the market. These systems can be relatively inexpensive when growing for personal consumption and utilizing smaller systems. Some of these systems can also be made by hand, at home, if you have the time and materials.
Flood & Drain (Ebb & Flow) Systems
Flood and drain systems are probably the easiest hydroponic systems to use. They consist of simple, easy to use parts and function exactly as the name dictates – they flood root systems with nutrient-rich water and then quickly drain it away.
These systems utilize either a tray or a simple table to hold plants, with a reservoir usually sitting directly beneath. Water is pumped from the reservoir into the tray that fills with water and floods the root zones with water and nutrients. The water is then either drained back into the reservoir and reused, or drained directly to waste to never be seen again. Most growers opt to recycle their nutrient solution a few times before replacing it with fresh water and nutrients.
In a flood and drain system growers can use a variety of grow mediums to house their plants. The most popular choice in this system are netted pots which have mostly open sides and bottoms that allow for easy soaking and draining. These pots are filled with clay pebbles, or hardened expanded clay (HEC), which look like brown or red clay marbles and are made by a few different companies. The HEC usually holds the plugs in which seedlings or cuttings were first started in, but once they acclimate to the hydro system the roots will begin to grow out over the HEC and into the bottom of the tray. Once the nutrient solution has drained, roots are left with an abundance of air for oxygen consumption. Trays are commonly flooded two to three times day for a few minutes at a time depending on the stage of growth the garden is in.
Top-Feed Drip or Spray-Emitter Systems
Top-feed grow systems may now have taken over flood-and-drain systems as the most common hydroponic systems in use by indoor growers. These systems contrast flood-and-drain systems by allowing growers to precisely control the exact amounts of nutrient solution fed to each plant site. Both drip and spray emitters come rated by output volume so that growers can calculate how long they want to feed their garden.
Emitter systems are predominantly used with either Rockwool or soilless mixtures that sit inside trays used to collect the run-off. These are the same trays (usually 4’ x 4’ or 4’ x 8’) that are used in flood-and-drain systems. The Rockwool medium can be of any format including large cubes, long slabs or crouton-sized cubes in container pots. Soilless mixtures tend to work best, however, and are held in either container pots or bags. Most top-feed emitter systems drain-to-waste as grow mediums, especially the soilless mixes, tend to add too many impurities to recycle the nutrient solution. In these drain-to-waste scenarios, larger reservoirs are needed to feed gardens two or even three times daily.
In drip systems, emitters are usually set to a constant, very slow flow of water. Thin spaghetti-tube lines run to Rockwool cubes holding plants. Emitters are easily held in media with tiny stakes and the constant drip keeps the medium constantly moist. Savvy growers, however, allow their mediums to completely dry out once every few days.
Similarly, spray systems also utilize spaghetti lines to carry nutrient water to spray nozzles that are staked in medium. These systems are set to a specific schedule of spraying that keeps the roots zone perpetually moist. It should be noted that spray systems usually require higher water pressure in the lines and thus more powerful pumps. Nozzle heads are also very delicate and can get clogged by nutrients easily. Make sure your nutrients can be completely dissolved in reservoirs before trying to use them in spray systems. Organic nutrients, unless micronized, usually have the most problems with spray nozzles.
Deep Water Culture (DWC) Systems
Deep water culture (DWC) systems are usually constructed out of large (5-gallon) buckets and are sometimes referred to as “bucket systems.” In this system, plants are held in net pots filled with clay pebbles or a similar type of stone. Plants may be rooted in Rockwool or peat plugs as seedlings or clones first and then transplanted into the net pots that sit suspended in hole cut in the lid of a bucket.
DWC systems can consist of one bucket, but are usually comprised of multiple buckets that are connected to together via hoses that circle back to a main reservoir. The reservoir holds the nutrient solution and a submersible pump that works on a timer. The pump periodically fills the buckets with water and nutrients which saturate the hanging root systems inside each bucket. When the pump stops, the nutrient solution drains back into the main reservoir to be reused in the next feeding.
A DWC system is excellent for small indoor growrooms with higher ceilings, as the buckets tend to produce tall, robust plants. The extra air available to root systems when the buckets aren’t fill enable large root structure to form, which in turn leads to fully developed mature plants. Up to ten buckets can be linked together via hosing and fed from a single-barrel (50-gallon) reservoir.
Nutrient Film Technique (NFT) Systems
Nutrient Film Technique, or NFT, is another easy-to-use system for hydroponic growing, though their popularity is waning in indoor horticulture. In this scenario, a thin film of water is run past the root systems, usually on a tilted table or tray for easy drainage. The roots, most commonly hanging out of netted pots, sap up the nutrient water that is pumped to the grow table from a reservoir.
In NFT systems, nutrient solution can be recycled or drained-to-waste and there is a lot more flexibility for growers in determining the feeding schedule for their garden. Because the root zones are not completely inundated with water, they do not get smothered and have less of a chance for drowning. The thin film of water running over them also moves a lot of air past the roots, carrying valuable oxygen molecules for uptake with H2O and minerals. Because of this, growers using NFT can choose to run a constant flow of water over the roots, knowing that plenty of oxygen is still provided to the roots. Most NFT cultivates, however, choose to run multiple feeding cycles per day, sometimes for as long as 30 minutes at a time. This largely depends upon the genetic strain being grown.
As long as ample oxygen is provided to the roots, root systems in NFT systems can stay very compact, as they do not need to search very far for nutrition. Top sections of roots zones can breath while the bottom sections dip into the think film of nutrient water, sapping up solid foods. It is important to remember that when using NFT, or any hydroponic system for that matter, plants need more air than water. A common danger of hydroponics is lack of oxygen to the roots. Roots should always be bright white; any sign of browning roots is a sure indication that your roots are being deprived of air.