The Main Methods of Hydroponics

As one of many branches of hydroculture, hydroponics is an umbrella term covering many related but distinct techniques. Each system has its own advantages and disadvantages, and the choice of a specific technique should be based on your specific conditions. A floating raft system may work better in a large commercial system than a backyard, while the passive design of wicking beds may make them more attractive to growers with little to no electricity available. Compare and contrast the various options for hydroponic systems to choose the right one for your business or hobby needs.

Floating Rafts and Deep Water Culture

One of the original forms of hydroponics is known as deep water culture (DWC) today. You’ll also find it referred to as the raft method since it relies on floating rafts, or even the aeration technique thanks to the air pumps required to oxygenate the water. Nutrient rich water is pumped into a tank, trough, pond, or other water feature of a certain depth. Floating rafts rest on the surface and contain small pots with soilless growing medium packed in. The plants grow in these pots, with the roots reaching through the bottom and into the nutrient-rich water below. The water may be constantly circulated or may stay in the tank for a specific period time. Aeration is necessarily either way, so bubblers and air stones help bring oxygen to the roots.

Benefits

  • Inexpensive to setup and operate when compared to other equipment
  • Works well with other systems like aquaponics and aquaculture
  • Easily based around reliable in-ground ponds and trenches rather than expensive tanks
  • Rafts are reusable when built correctly
  • Greater stability in plant growth thanks to constant exposure to water and nutrients
  • Allows for both recirculating and non-circulating use.

Disadvantages

  • Requires constant attention and water quality management through reservoir tanks and sensors
  • Greater chance of failure if a water or air pump breaks
  • Harder to calibrate proper nutrient levels in very small hobby systems
  • Allows for less control over which individual crops receive what level of nutrients.

Drip Systems

Instead of letting the plant float in water and potentially receive too little oxygen, you can also build a bed or pot of a soilless growing medium and simply drip the nutrient rich water through it. This gives the roots the same support and air pockets of soil without the disease and nutrient-binding effects that come with it. Drip systems are highly water efficient and don’t require you to store a lot of water at once, especially in small hobby systems. They also need fewer pumps than DWC, but rely more on the water pumps that are part of the system.

Benefits

  • Widely used around the world, offering a lot of practical experience and knowledge for your own system
  • Works well for both recirculating and non-circulating designs
  • Can be scaled to a very small tabletop size without much loss of efficiency or control over nutrient levels
  • Most resistant to crop loss during a power outage since the nutrients and water don’t disappear when the pumps stop
  • Less catastrophic effects if the air pumps fail in the system since the roots can reach air, but water pump failures are still dangerous
  • Separated reservoir in recirculating system makes it easier to test and adjust water quality parameters away from sensitive roots.

Disadvantages

  • Still requires nearly as much water quality testing and adjustment as a deep water system
  • Can be more expensive to set up than rafts due to the greater amount of soilless growing medium needed
  • Requires timers that can fail
  • Drip irrigation lines easily clog due to the mineral content of the nutrient solution, which can kill off entire crops that miss a few flushes.

Nutrient Film Techniques

Nutrient film techniques (NFT) were designed to cut water use as much as possible in hydroponics without losing valuable plant growth. It’s a more advanced system than older raft and drip technology, but it’s also more complex and full of potential failure points. Beginners should get some experience with the other methods before setting up a nutrient film system in most cases since it’s generally based on the most expensive equipment. If you think of long rows of PVC pipes or tubes when you hear the word hydroponics, you’re picturing NFT systems. Water runs down the inside of a slightly angled tube, delivering water to the roots with only a thin film necessary to keep up the flow. While these systems are compact and space-saving, they’re also delicate and require plenty of attention.

Benefits

  • Water quality stays stable due to less exposure to air and roots, reducing testing and adjustments
  • Requires little to no growing medium since plants often sit directly in plastic mesh pots
  • No aeration needed around the roots since so much is exposed to the air
  • Reduced waste and loss of valuable nutrient solutions
  • Lower cost of ongoing production due to reduced need for water treatment and new growing medium
  • Doesn’t require timers like a drip system since the film is constantly flowing

Disadvantages

  • Requires more pumps, sensors, and high-tech components than other hydroponic techniques
  • Susceptible to power outages since even a few hours without the water film will dry out the plants beyond recovery
  • Harder to get every detail right from the beginning, leading to more initial losses as problems are found and solved
  • Generally requires re-circulation since the constant flow would otherwise waste a lot of nutrient solution.

Ebb and Flow

For a compromise between the drip and deep water systems, consider ebb and flow designs. Rather than fed a regular trickle or film of water, plants are flooded every few hours to wet their roots and give them a chance to absorb nutrients. Letting the water recede between flows introduces oxygen without air pumps. Pumps only turn on for the surge, leading to lower energy costs. The timers can be set to accommodate any flooding pattern, allowing you to grow water loving crops in one area and drier plants in another.

Advantages

  • Less susceptible to drying out during power loss than film or drip methods, but still more sensitive than deep water culture
  • Allows more options for how plants are rooted, from entire beds full of growing medium to individual pots you can remove at any time
  • Use of water-holding growing mediums reduce the frequency of flooding events per day
  • Requires a stronger nutrient solution, and therefore more fertilizer costs, than methods with constant exposure.

Disadvantages

  • Requires plenty of growing medium to support the roots as they’re flooded
  • May not support a steady plant growth curve as well as other methods unless the timing of the flow is perfect for the particular plant
  • Usually requires recirculation to supply enough water for flooding that’s properly mixed with nutrients
  • Can overflow and make a mess due to clogged overflow pipes and other issues.

Wicks for Water Lifting

For a fully passive hydroponics system that doesn’t need pumps, consider the wicking system. A reservoir holds the nutrient solution below the plants where the roots can’t reach it. Wicks draw the liquid up from the reservoir and into the root zone tank. This tank must be filled with a water-holding growing medium to complete the wick effect and actually draw moisture to the roots. The wicks act similarly to the roots of the plant but won’t continue to grow and deliver too much water. The resevoir still needs aeration in some way, so you’ll need to at least change out the water regularly if you can’t use an air pump.

Benefits

  • Can work with no electricity at all and in situations where pumps aren’t available
  • Works with the widest range of growing mediums, including inexpensive peat moss, coconut coir, and perlite
  • Can be made from salvaged materials for small hobby projects
  • Makes no noise and less humidity than other systems, making it more attractive for indoor use.

Disadvantages

  • Hard to scale to a commercial system
  • Doesn’t optimize plant growth rates as much as the other systems
  • Plants can demand more moisture than the wicks can provide, especially in hot weather or during fruiting
  • Requires regular and manual refilling of the reservoir in most systems
  • Wicks can break or stop drawing water with no visible problems until crops dry out.

Between these methods and the futuristic field of aeroponics, there’s plenty of options to choose from for your hobby or business designs. You may want to set up a few different units and compare them directly before making a decision about which to use for your purposes. No matter the system you choose, you can adjust it to use custom built ponds or tanks. Create your own custom hydroponics designs instead of feeling limited by kits by working with BTL Liners.


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