Different Types of  Hydroponics Systems

There are many different types of Hydroponics systems.  Theoretically, the aeroponics is better than hydroponics in terms of plant growth. However, due to technical and environmental limitations in urban farmers, these made only minor differences.

Of all these systems, I recommend urban farmers living in small apartments to try the simplest kratky method first, starting with a small plant, that gradually experiment that other types that feed your environment. The Autopot / auto water level controller is my favourite hydroponics  growing method now. I have created some projects to 3D print such water level controllers. Please reference my blog or youtube channel.

https://youtu.be/7lKQy4rfRNM

or you can make them using pill box and platsic bottles.

https://youtu.be/jFU-bGxyo_Y

We can break down into two main types:

I. Circulating Systems (active systems)

DFT or DWC

Deep Flow Technique or Deep Water systems ensure plant roots are always submerged in water without necessitating that water be pumped to the root zone. To avoid drowning the roots, a air pump or water pump will help to  aerate and oxygenate the solution evenly and constantly.

NFT

NFT  (Nutrient Film Technique) is a hydroponics system set up with growth pipes slanting downwards. Holes are drilled. on the pipe. Plants are inserted with roots touching the floor of the pipe. Nutrients are constantly pumped up to the top of the pipe and flows down forming a very thin layer of nutrient. There are various ways to design a nutrient film technique system; however, all of them take after the design of a very shallow nutrient solution pouring down through the tubing. The bare roots of the plants will absorb the nutrients in the solutions when they come into contact with the water. 

Pro:

Because the root is constantly exposed in air (only the tip is touching the nutrient), it is greatly aerated and can enjoy a healthy grow.

Con:

As it's an active system, there is a risk that the entire corp will be lost when the pumps failed, or pipes are cogged or there is a power outage.

For a recycling system as the used nutrient returned to the big nutrient tank feed back to the plant. The plant is like drinking from the toilet. And to void worsening conditions, you need to constantly monitor the PH and EC and put in additional solutions to adjust them.

Ebb and Flow or Flood and Drain

Ebb and Flow or Flood and Drain works in a similar fashion as NFT that  use water pumps to deliver the nutrients to your plants.  Except that the growth tank for Ebb and Flow can be horizontal. Water level rises up to the required level, then the pump stops and water level drops as the nutrient are drained back to the nutrient tank for an extended period, usually in minutes. However,   the NFT system is a constantly flowing one and the nutrient water level will be roughly constant through out the day.

Pro:

Easy to set up and lower cost compared to NFT.

Con:

For a recycling system as the used nutrient returned to the big nutrient tank feed back to the plant. The plant is like drinking from the toilet. And to void worsening conditions, you need to constantly monitor the PH and EC and put in additional solutions to adjust them.

Dripping or Trickle or Micro Irrigation

A drip system uses a pump to feed your plants with nutrients and water regularly. The system uses small emitters to drip the nutrient solution directly onto your plants. Excessive nutrient are passed back to the nutrient tank to be reused.

Pro:

Better control over ebb and flow and NFT.

Con:

For drip system that is circulating, it has the same issue as all circulating system that the returned / used nutrients is being recycled and continue to impact the PH and EC and require regular check and adjustment.

As with all active systems, anything can break. power. pump, clog and ruin the whole corp.

Aeroponics , Misting 

Pro:

Better control over ebb and flow and NFT.

Con:

For drip system that is circulating, it has the same issue as all circulating system that the returned / used nutrients is being recycled and continue to impact the PH and EC and require regular check and adjustment.

As with all active systems, anything can break. power. pump, clog and ruin the whole corp.

Fogponics

Pros

Tiny sized droplets. Great coverage

High nutrient concentration

Easy to clean

Cons

Heats from the atomizer / fogger will build up over time. The fogger need to be turned off every 4 hours for 1 hour.

Built up salt.

Salt accumulates in the system flogging the foggers and need to be cleaned up regularly.

Corp will be lost if there is any poiwer outage.

High initial and maintenance cost.

Fogger tends to fail easily and increase the replacement cost.

II. Non-circulating systems (passive systems)

Wicking

A wick system  use the capillary action of water to draw up water and nutrients from a reservoir to the plants. Since we are talking about hydroponics, plants will be some sort of grow medium, not soil.

Each plant will have at least one wick, preferably two, connecting it to the reservoir. The latter is usually placed immediately below the growing surface or tray for maximum effectiveness.

Due to capillary action, the water and dissolved nutrients will travel from the reservoir up to the plants through the wicks. That is all there is to a wicking hydroponic system.

Pro: Easy to set up

Con: Not suitable for water hungry plants

Kratky Method

Invented by Benard Kratky - researcher in the university of Hawaii, this is a passive non-circulating method. You first found a grow tank that is bing enough to contain all the nutrient for the entire life of the plant from seedling to harvest.

Then fill it up with Nutrient to a high level touching the root of the seedling. 

As the plan grow taller and the roots grow longer, the nutrient level drops making enough space for air inside the grow tank to aerate the roots. This will provide a reasonably good harvest without much investment on pumps, and electricity.

Con:

This is suitable for leavy plants or vegatble, but less suitable for plants that need a longer time to harvest, e.g. fruits as the nutrient may dry out and need to be refilled quickly.

Pro:

A modification of the Kartky method  is to get a big nutrient tank to feed the growth tank and use a water level controller to start feeding only when the nutrient level drops beyond the low level mark. 

Autopot - Passive high and low water level controller

Autopot and SmartValve is a registered trade mark and the product.

Please refer to the official site for the commercial products. 

https://www.autopot.com.au/accessories

This page will only explain the mechanism.

The autopot system is based on a passive high and low level water level controller.

A big nutrient tank located at a high level as the grow tank is used to feed nutrient through a valve. Gravitational force pushes nutrients from the nutrient tank to the pipe that connects to the grow tank. 

The valve control the inflow of nutrient to fill the growth tank up to a high level mark, which is usually kept at 1 inch to allow enough air space to aerate the roots.

When plant absorb the nutrient and cause the nutrient level to drop, nutrient will not be replenished until the nutrient level drops below a low level mark. This is similar to the high tide or low tide in the ocean. 

Pro:

The system is easy to deploy and do not require electricity. 

The plant determines when nutrient will be replenished by itself. 

No environmental pollution. The nutrient is all absorbed by the plant, no waste.

Nutrient is feed to individual growth tank and controlled by a valve. this avoided spreading of virus and disease.

No recycling - No need to adjust PH and EC once the Nutrient solution is created. For a recycling system as the used nutrient returned to the big nutrient tank feed back to the plant. The plant is like drinking from the toilet. And to void worsening conditions, you need to constantly monitor the PH and EC and put in additional solutions to adjust them.

Con:

Feeding of nutrient is through thin ducts that can be cogged by algae some times and need regular maintenance.