It may seem confusing with all the different looking hydroponic systems out there. Not to mention all the different names and terminology company’s use to hype their products to make them sound new, exciting and revolutionary; the new this system, the new that system, the revolutionary this method, the revolutionary that method, etc. But it’s actually easy to separate all the hype and fancy terminology from function and understand how any hydroponic system actually works.
The first thing to understand is that there are actually only 6 types of hydroponic systems. Every hydroponic system out there is one of these six types, and/or a combination of two or more of these six types. If you understand the difference between the six types, you’ll always be able to tell what type of system any hydroponic system is. So what makes the six types different?
It’s all about how the water/moisture, nutrients/food, and oxygen/air are delivered to the plants roots. Each of the six types of systems provides these three important elements to the roots in different ways and amounts, and that is what makes them different. Each type of system has its pros and cons, and you can easily combine aspects of more than one type of system to change or improve how any of these three aspects are delivered to the root systems.
Along with the six different types of hydroponic systems, there is a sub category of recirculating or non-recirculating, may also be referred to as a recovery/non-recovery system. This simply refers to whether the water/nutrient solution is collected after it runs through the system, and then pumped through the system again. Most home gardeners and hobby growers recirculate their nutrient solution.
But on a large scale, in many cases it is much more practical for commercial growers to run the system as a non-recirculating system, also called “run to waste”. It sounds wasteful on water and nutrients, but the amount of water and nutrients are precisely controlled and it actually uses less water and nutrients than a recirculating system.
A drip system is basically just as it sounds. Water/nutrient solution is pumped through water lines to the base of the plant where it drips out and drains down through the growing media to the bottom to keep the roots and growing media moist. That provides both moisture and nutrients for the roots.
The amount of moisture is controlled by the amount of water being pumped to the plants. The nutrients are controlled by the strength of nutrient solution. Oxygen is supplied to the roots through aeration in the growing media. As the water drains downward, it pulls fresh air/oxygen down into it as well. The type of growing media will also make a big difference in moisture and oxygen levels to the roots.
Flood and drain systems are also basically just as it sounds. Water/nutrient solution is pumped from a holding tank called a reservoir, up to another container that holds the plants roots. There is an overflow tube that allows any excess water to be drained back to the reservoir before it spills out. Then once the pump is shut off the water drains back down into the reservoir through the pump. The pump is turned on and off by a simple timer. As the water drains out of the root zone, it pulls fresh air/oxygen back down into the growing media/root zone with it.
Nutrient Film Technique) systems use rows of some type of tubing set on a slight angle. Water/nutrient solution is pumped up to the top level, or split equally between several tubes/sections on the same level. The nutrient solution is continually pumped into one side of the tube, and gravity feeds/drains it to the other side because of the angle/slope of the tubing. The amount of slope is usually about 1 inch for every 3 feet of tubing.
This slope allows a thin film of nutrient solution to drain downhill past each plant in the row. The plants are suspended above this film of nutrient solution and the roots hang down into it. Water and nutrients are supplied by the nutrient solutio. and controlled by the flow rate of the water. Oxygen is supplied to the roots that are hanging above the film of nutrient solution.
Water culture systems are one of the simplest hydroponic systems to build. Instead of a water pump pumping water from the reservoir to the plant roots, the plant roots hang down and are suspended directly in the reservoir. An air pump is used to create air bubbles in the reservoir and is the only moving part in a water culture system. Water and nutrients are provided to the roots by hanging down directly in the reservoir.
Oxygen is provided to the roots through the air pump and air stone creating the air bubbles in the reservoir. The air bubbles not only provide oxygen, but also create water movement that keeps the nutrient solution evenly mixed up, and keep the nutrients in the water from settling to the bottom.
Aeroponic systems can be the most complicated of the 6 types. With aeroponic systems the plants roots hang in midair, and use very little if any growing media at all. The nutrient solution is pumped to mister/sprinkler heads that spray the entire root system. Because the roots will dry out much quicker hanging in midair, they need to be sprayed at frequent intervals. Generally a special timer called a cycle timer is used to spray the roots in short but frequent intervals.
There are two types of aeroponic systems, a high pressure system and a low pressure system. A high pressure system is a true aeroponic system, and uses upwards of 60 PSI or more to spray a fine mist on the roots. A low pressure system is much more commonly used because it’s much less complicated than a high pressure system. With low pressure systems you can use regular water pumps and sprinkler heads to spray droplets onto the roots. Low pressure systems are sometimes referred to as soakaponics because the water droplet size is much larger than with high pressure systems.
High pressure systems require a pressurized accumulation tank and a solenoid valve to open and close the water line to the misters. With aeroponic systems, water/moisture and nutrients are controlled by the cycle timing and nutrient strength. They also provide the most oxygen to the roots because they hang in the air. Also high pressure systems allow more air to get to the roots than low pressure systems because of the much smaller water droplet size.
Wick systems are the simplest of all of the hydroponic systems. That’s because there are no moving parts and no electricity is needed to run pumps or timers. It also works like it sounds. The plant sits in a container filled with good water absorbing growing media. This container has a few strips of a good wicking material in it that hang down through the bottom of it. Then it is placed on top of the reservoir so the strips of wicking material hang down into the nutrient solution and wick it up into the growing media with the plants in it.
Some of the most commonly used wicking materials are strips of fabric from old clothing or blankets, cotton rope, propylene felt strips, rayon rope or mop head strands, wool felt, wool rope or strips, tiki-torch wicks, braided polyurethane yarn and nylon rope. Regardless of what you use, make sure to pre-soak the wick first. Water/moisture and nutrients are controlled by the type of growing media used as well as the size and how many wicks are used. Oxygen is delivered to the roots by the natural air pockets between the partials in the growing media used (bigger pockets, more air to the roots), much the same way it is with a potted plant growing in potting soil.
Notice how each of the six types of hydroponic systems gets water, nutrients and oxygen to the plants roots in slightly different ways. How you build, design and run the system will determine how much or little water, nutrients, and/or oxygen the plants roots have access to and thus can use. Also you can combine aspects of one system with another system to help increase or decrease how well each is delivered to the roots, and fit the needs of the plant.
Now I know what you’re going to say, “What about aquaponic systems?” Well the fact is aquaponics is not a seventh type of hydroponic system. It’s actually a method of manufacturing your own nutrients through fish waste and bio-filters. This fish waste nutrient solution can be used in any of the six types of hydroponic systems.
Simply replacing the regular nutrient solution reservoir with a fish tank reservoir will change your hydroponic system into aquaponics. By the same token changing from standard hydroponic nutrients, to organic nutrients is basically the same thing. Except that the fish continually add/make the nutrients themselves and when the fish get bigger you can eat the fish too.
Jeff Sanders runs a hydroponics website called HomeHydroSystems.com to help hydroponics enthusiast learn how to build their own hydroponic systems, as well as learn about many topics related to hydroponics so they can grow to their own crops successfully. He is a hydroponic gardener and enthusiast with over 7 years of experience growing hydroponically. He is also currently building a small commercial hydroponic greenhouse to grow live fresh herbs to sell in his local continuity. You can contact him through his website.