Hydroponics is generally defined as the practice of growing plants without using soil, but how exactly do we go about doing that? Does it matter? How do I choose which method is best? In this article, we will explain the various system designs that are commonly used to Hydroponically grow plants, and give advice about which systems suit what you want to grow!

The 3 Main Types:

As the above suggests, every system that exists for Hydroponics generally falls under one of the three main system types. These are Recirculating (R) Systems, Run-To-Waste (R2W), and Deep-Water-Culture (DWC).

Recirculating (R) Systems are defined as systems where the nutrient solution is pumped from a reservoir to the plants' roots, and then any excess or "run-off" nutrients are allowed to drain back into the same reservoir for reuse. This means that Nutrients are allowed to be fed to the plant(s) over and over again until the Nutrients are either fully used or contaminated.

Advantages of R Systems:

• R systems are generally very nutrient efficient and very suited to larger scale commercial operations. (Later on in the article we will explain the various sub-types of R Systems, and it will become clear as to why they are favored in commercial operations.)
• These systems often either use mediums with very poor water retention, or no medium at all,  meaning it is harder to run into problems like root rot and it is much harder for soil-based pests to live in the mediums.
• The amount of medium required in these systems is generally much less compared to other systems.
• Regular feeding and flushing helps prevent salt buildups and helps achieve uniform pH and EC in the root zones.

Important Considerations:

• R Systems are not compatible with Coco-Coir, or any other 'soil-like' medium as due to the fibrous consistency, loose bits that flow out with the run-off can clog feed lines and more importantly, the nutrient pump. 
• Generally, in R Systems, the reservoir solution is only topped up or replaced once a week or sometimes even less frequently, therefore organic nutrients are not compatible with R systems, as organic nutrients will not last more than 3 days in a reservoir and will produce nasty biofilm and buildup, causing issues within the system.
• Greater consideration towards cleanliness and disease prevention is also necessary, as any infected plant can get other plants in the system afflicted much easier due to all being connected within the loop.
• If pump failure occurs, plants can be lost very quickly due to the lower water retention of the mediums commonly used in R Systems.

R Systems exist in a few different configurations, several of which we'll show below. These are the most common configurations used by Hydroponic growers:

Nutrient Film Technique (NFT):

Plants in NFT Systems are planted into elongated sloping irrigation channels where roots have no medium support and are fed by introducing nutrient at the high point of the channels. The nutrient then flows down along the irrigation channels where it reaches a drainage point and is returned to the reservoir to be pumped back up again. 

The feed cycle can either be run 24/7 or intermittently, with several feeds occurring an hour. Intermittent feeding allows the roots to access fresh oxygen between feeds. NFT Systems are favoured by commercial operations, as they can be very water, nutrient, and space efficient and are very effective for growing leafy greens, herbs, tomatoes, capsicums and other common commercial crops. 

NFT Systems make it easy to access plant roots for inspection and maintenance, which is excellent for root health. Ensuring the channels are appropriately sized for the plants and placed at the correct gradient is absolutely key to the success of an NFT System. 

Because NFT Systems usually have no medium, be cautious of pump failure as this will result in plant death in a few hours!

If done correctly are extremely efficient at specifically leafy green and herb production. NFT Systems are not suitable for plants with large tap roots (i.e. potatoes and carrots).

NFT Systems work great both indoors and outdoors, depending on space and lighting available 

We'd recommend an NFT System for the following plant varieties:

• Lettuce Varieties
• Asian Greens (Pak-Choy etc.)
• Strawberries
• Herb Varieties excluding Mint (Mint will grow fantastically well in an NFT but the roots have a tendency to take over the system)
• Edible Flowers (Pansies etc.)
• Broccoli
• Cucumbers
• Beans

If you think an NFT System sounds like the system for you, be sure to check out The Salad Table NFT Kit!  which is a fantastic kit that'll get you growing your leafy greens in no time!

Flood and Drain (Ebb and Flow):

In these systems, nutrient is fed to the plant(s) via flooding the rootzone from the bottom up, and then the nutrient solution is allowed to drain back into the reservoir. This is done through an inlet in the bottom of the planting tray to allow for flooding and drainage, and an overflow to ensure the waterline does not go above desired level.

Flood and Drain systems are fed intermittently and allow for a constant exchange of fresh oxygen and nutrient solution. Clay Balls are the medium of choice for most flood and drain systems, as they have very low water retention and the nutrient solution must drain completely between feeds. 

The flooding process helps stop salt buildup and helps achieve uniform root pH and EC. The flooding action purges stale oxygen from the roots and the draining action draws in fresh oxygen to the roots, which will keep the plants happy!

Much like NFT Systems, pump failure can result in plant death if not monitored, and care must be taken to ensure that pump timing is set to allow for adequate flooding. Proper care to ensure drainage is clear from blockage is also very important as to prevent overflooding/waterlogging. 

Flood and Drain Systems are very similar to NFTs in performance, however Flood and Drain systems can accommodate for larger plant varieties, and so we'd recommend Flood and Drain Systems for the following plant varieties:

• Everything you can grow in an NFT System
• Potatoes and Carrots (Yes, you actually can do this if you make your flooding area deep enough)
• Tomatoes
• Capsicums
• Chillies

If you're interested in setting up a flood and drain system check out our range of Trays and our fittings set to get started! Or see us in-store for help building a system!

Aeroponics:

Aeroponics systems require no media and are defined as systems where the root systems are freely suspended in a well ventilated reservoir. The nutrient is delivered through spray jets as a fine mist using a high pressure pump. The immediate benefit of these systems is the lack of medium cost, disposal and handling. As an extension to this benefit, the roost are going to be in a constant well-oxygenated environment and are going to be very easy to inspect and clean. Root Zone EC and pH are going to be equal to that of the nutrient solution due to the direct application from the spray jets.

Due to how small spray jets are, they can be prone to blockage so it's important to have everything filtered well so that issue is reduced. Additionally, due to high evaporation losses in true Aeroponic systems, nutrient solution will need to be topped up more often to avoid salt buildup.

Aeroponics probably have some of the most efficient nutrient delivery out there and they also make excellent propagation systems as the little roots of baby plants have an easier time handling mist and well oxygenated environments.

If you have the space for the roots, you can pretty much grow anything, however we recommend Aeroponics for the following applications:

• Small aeroponic systems designed for propagation are excellent at ensuring strong early growth. The Seahawk Cone Station and the TurboKlone are excellent examples of this. 
• Hydroponic towers, such as the Airgarden, are great for space efficient growing of Leafy Greens and Herb Varieties!

Satellite Systems: 

Satellite Systems are when one or more independent pots are connected to a central nutrient reservoir. These systems are probably the most commonly used in the realm of the home grower as they are very flexible as pots can be added/removed without disturbing other plants, and these systems are very good for plants with larger root systems. In Satellite Systems, most often Nutrient is pumped to the top of the pots, which have multiple holes for drainage at the bottom. These pots are usually nested inside another pot that collects all the run-off, and drainage is fed back to the reservoir from these collection pots. These systems are commonly configured as Run-to-Waste systems (below) which makes them compatible with more mediums and organic nutrients!

We'd recommend Satellite systems for the following applications:

• Chillies
• Capsicums
• Tomatoes
• All Types of fruit trees, especially dwarf varieties
• Berries
• Cucumbers, Squash, Pumpkins (provided you can train the vines!)

If you'd like to piece together a Satellite system, come see us in store and we"ll help you design a system for your needs!

Additionally, you can check out the all-in-one Wilma XL 4, which is a 4 Pot Recirculating Satellite System that is very easy to setup and use!

Run-To-Waste (R2W) Systems are similar to R Systems where nutrient solution is pumped to the roots of the plant(s) but the main difference is that the run-off does not return to the same reservoir but instead drains to a collection reservoir or is directly drained to the ground below.

Advantages of R2W:

• If collected, the EC (Electrical Conductivity) of the run-off can be tested to see exactly how much the plant(s) are feeding. This can assist in knowing when to increase or decrease nutrient concentration to prevent, deficiencies, burning, or wastage.
• The amount of run-off can be measured to ensure that the plant(s) are not being over or under-watered. Generally, aiming for a 10% - 20% run-off from the amount of nutrient solution watered in is ideal. 
• Nutrient solution is not fed back to the reservoir after traveling through the root systems, therefore if any plant becomes sick, it will not spread through the system.
• Organic Nutrients are compatible with R2W, as they are not returned to the reservoir and will therefore not cause buildup.
• Plants receive only fresh Nutrient every feed.
• If pump failure occurs, plants will not dry out as quickly due to the higher water retention of the mediums commonly used in R2W Systems.

Important Considerations for R2W:

• Feeds are less frequent compared to R Systems, thus salt build up will occur, so flushing is very important in R2W Systems.
• Due to the water retention of mediums commonly used in R2W, water-logging may occur if over-watering, and thus greater attention to proper watering is required.
• Care must be taken when disposing of run-off, as this can have environmental impacts if not disposed of responsibly (i.e., contamination of groundwater)

Essentially, all the systems we've talked about previously with R systems can be configured to be Run-To-Waste! You just need to send the run-off to another collection point! You can grow all the same plants in these systems as you can with R systems, it just allows for more precision when watering/feeding, and allows you to use R2W specific mediums like coco-coir and rockwool, as well as organic nutrients!

Come see us in-store for help on building your own R2W system!

Deep-Water-Culture (DWC) Systems are defined as systems where the plant(s)' roots are fully submerged in nutrient and oxygen-rich water solution. There is no run-off because the crop is essentially sitting in the reservoir itself. These are also known as Raft Systems.

Advantages of DWC:

• At their core, DWC Systems are very simple and compact, meaning they can be very space-efficient.
• No pumps are required, except for maybe an air stone to achieve optimum oxygen levels on the water.
• Roots will not dry out, as long as water levels are maintained.
• Very efficient delivery of Nutrient as it is always available to the plant(s).
• pH and EC are easy to maintain and manage.

Important Considerations for DWC:

• Water temperature is extremely important to maintain in DWC. If the plant(s) are sitting in water that is either too hot or too cold, then nutrient lockout and stunted growth is likely to occur.
• If you live in hotter areas, you're going to need a water chiller to keep your temperature stable!
• For colder areas, you're going to need a water Heater to keep your temperature stable!
• If you live in an area that can't decide what temperature it is, you'll probably need both a chiller and a heater to maintain stable temperature.
• Organic Nutrients are not compatible with DWC for the same reasons they are not compatible with R Systems.
• Mediums with high water retention are not suitable for DWC. In DWC, Plants are generally held in netted pots, and need some form of medium to hold the plants in place. Expanded clay balls are generally the preferred medium as they have excellent aeration and extremely low water retention, meaning the medium will not soak up or hold water, preventing issues like root rot.

You can generally grow most plants in DWC systems as long as they are not species that cannot have their roots constantly drenched, i.e, you wouldn't grow Tap root vegetables like carrots and potatoes in DWC.

If you'd like to try DWC, we recommend The Oxy Pot 2 XL Set and Air Pump DWC Kit, it's perfect for trying out DWC and is super simple to setup and use!

If you're looking for temperature control, we recommend checking out the Hailea HC-100a 1/20hp Chiller to keep your water cool, and one of our Aqua One Water Heaters to warm up water!

HONOURABLE MENTION: WICK FEEDING SYSTEMS

So wick feeding systems aren't strictly locked into being hydroponic systems but do have versions that are classed as Hydroponics. Wick Feeding Systems are simply when water is introduced to the bottom of the pot and the medium inside soaks it up for the plant to then feed on. If you've ever had a little pot plant sitting in a saucer of water before, that's a wick feeding system! Where it becomes Hydroponics is if you have your plant sitting in a medium that isn't soil and you regulate the water supply via a float valve hooked up to a reservoir.

The simplest way to do that is getting yourself one of the Autopot kits! These things are brilliant especially for chillies, capsicums and tomatoes! Gravity makes the nutrient solution travel to the base of the pot, where the smart-valve lets water in until it reaches its shutoff point, then as the plant wicks up the water in the base of the pot, the smart-valve opens up again to let new nutrient solution in! The plant waters itself and there are no pumps or timers required!

Which to Pick?

Ultimately, the system that you should choose is very dependent on your current situation. It depends what you want to grow, how much space you have, how complex a system you are comfortable with, and available budget. As we've mentioned above, some systems are better suited for certain plants, so if you decide what you'd like to grow first, the other factors should quickly fall into place.

If you're really unsure you can certainly send us an inquiry or come and see us in store, after all, our business is to help you grow!