Hydroponic Systems: A Guide to Growing Plants in Water

Hydroponic systems are different approaches to growing plants in water, often supplemented with other mediums such as coco coir. Most popular systems include Deep Water Culture, Ebb and Flow, NFT, DFT, wick systems and various drip systems as well.

Growing plants in soil is something humans have done for thousands of years. Some plants, such as rice, can grow in flooded areas and survive being submerged for weeks at a time, which made growers ask the question “can plants be grown in water only”, and the answer is - yes!

In the last few decades hydroponic systems have developed into a branch of farming of their own as we now see two completely different approaches in growing plants. One of them was the traditional way of farming plants grown in soil as the medium for nutrients, and the other was using water as the only medium to feed the plant.

Hydroponic systems were introduced to the world in the late 19th century by William Frederick Gericke. He conducted an experiment at University of California in Berkeley which yielded a 25-foot high tomato vine. The result of this experiment showed the untapped potential of growing plants in water - or as he called it, hydroponics. He later wrote a book called “Soilless Gardening” which you can access here.

Indoor hydroponic systems

Indoor hydroponic systems have recently gained popularity in the world of cannabis growing. Prior to that they were already heavily used in growing all kinds of salads and greens. However, once cannabis started getting legalized, more and more people and companies started getting on board with them.

Water was once thought of as a necessary supplement to soil, as it was needed to feed the plant with nutrients from the soil. Complex outdoor irrigation systems were made, channels were dug up, billions of feet of hoses set in place, only for growers to find out they can completely remove soil from the equation. Simply put, indoor hydroponic systems revolutionized the farming industry.

How do you start a hydroponic system at home?

If you’re not looking to learn everything about hydroponics from the ground up, we suggest you get yourself an automated hydroponic system. Instead of experimenting with buckets, water tanks and all that, buying a pre-built system will speed up your prep phase and skip all of the handy-work.

Both AutoPot and Current Culture offer a great starters kit which will help you set everything up, without having to drill buckets and such. However, they are on the opposite sides of the price spectrum, and Current Culture is a bit more advanced technology-wise so if you are growing in water for the first time we strongly recommend you check out the AutoPot 4-pot system.

What is the best hydroponic system for beginners?

As we’ve just mentioned in the previous paragraph, the AutoPot hydroponic systems are a really good choice for beginners. They work as an ebb and flow hydroponic system, meaning that the water periodically rises and lowers within the bucket. According to the AutoPot website, the easy2grow models can also be used as an irrigation setup together with soil, meaning you pack the tank with water, and the rest of the pots with soil.

Do hydroponic systems need sunlight?

While all plants need light to grow. plants grown in hydroponics systems don’t need direct sunlight as hydroponic growing is most often done in an indoor setting. The plants are either partially exposed to sunlight and supplemented with other lights- such is the case with greenhouses, or completely grown under the cover of powerful growing lights - most often LEDs.

While you may achieve decent results with hydroponics outdoors, you won’t get the same results you would growing indoors in a heavily controlled setup. However, the sunlight and wind will reduce your cost per gram as you won’t have to pay for power or ventilation.

Types of hydroponic systems

In most common hydroponic systems plants are placed in a container filled with some type of medium, such as pebbles, coco, rockwool or similar, in order to give the plant some stability as the roots need to attach to something. Most professionals use either clay pebbles or rockwool, depending on several different factors.

Net pots are used to hold that medium, and then plants root out from the net pot down or outwards. Most systems also tend to rely on the water within the system circulating the nutrients to your plants all the time, thus saving up on your water bill as well.

Ebb and Flow

How it works: Ebb and Flow is one of the most common hydroponic principles as it basically imitates the tides in nature. The system imitates this natural occurrence by having the water go up and down within the container where we’ve placed the plants.

The ebb and flow hydroponic system relies on a pump to dish out the water and nutrients from the main reservoir to the individual plant containers, or a “raft tank” in the case of industrial growing. Once the tide is over, we turn off the pump and the water returns to the main tank through an overflow valve. Ebb and flow hydroponic systems require very little maintenance and are very efficient.

Keep in mind: If the roots are submerged under the water without access to at least some oxygen, they won’t grow and develop properly. We avoid doing that by aerating the roots when the water level in the container drops, and the water flows back in the main tank. Make sure you time your ebb and flow periods well, otherwise you might end up harming your plants.

DWC - Deep Water Culture

How it works: Deep Water Culture is another hydroponic system that takes little to no practice to understand and get better at. In this system plants are held in a water container from first to last week. Plants are again held in net pots with their roots completely submerged in water.

Just like with the ebb and flow system, plants don’t have to be in individual containers, they can also be held on a raft if you are growing on a big scale. Since this system is pretty self-reliant, you can leave it untouched for days or weeks at a time.

Keep in mind: The water in this system is static and rarely changed, which means that roots need to be oxygenated in some other way. This is done by introducing an air pump or air stones into the container. Air bubbles flow up from the bottom of the container and break against the roots, which helps the nutrients get into the plant much faster.

Drip irrigation

How it works: Drip irrigation systems are most commonly used as a watering system supplementing the main medium, most often soil. They rely on a system of valves, pipes, tubing and emitters to distribute water and nutrients in a minimalistic fashion. The tubing and pipes can be either on the surface of the soil, or buried just below the surface in order to send the water directly to the roots without any evaporation.

Drip systems can be recirculating and non-circulating, meaning that the water is either held within the system or released out. Recirculating systems are much more common as both the water and nutrients are not being thrown out, making the resource consumption a lot lower, as well as saving you money on the water bill.

Keep in mind: Drip systems are designed to preserve water. However, since they have lots of small but very important parts they require “soft” water (which won’t cause calcification after a while) and lots of maintenance. These systems often require manual checkups to see if leaks or cracks in tubing have formed which at times may cause a complete system failure.

NFT - Nutrient Film Technique

How it works: NFT, short for nutrient film technique, is a system in which the plants rely on a strip of nutrients, to which the roots have direct access. Plants are placed in net pots, and then in a sloped container which is often also called “the tube”.

The nutrients are dissolved in a very shallow water which flows through what’s called a gully or a channel. After that, the water is recirculated back into the tank from which it first came.

Keep in mind: NFT systems are among the harder systems to set up and maintain, as they depend on lots of different factors, such as the slope of the channels, flow rate, channel length, and lots more. If you’re just looking to get started with hydroponics, this would be a bad first choice for most growers.

DFT - Deep Flow Technique

How it works: The Deep Flow Technique is a cross between DWC and NFT, the two hydroponic systems we previously mentioned. Similarly to NFT, plants in net pots are placed in a sloped container, however the level of water is significantly higher than when using NFT. The high flow might cause the plant to tip over and be a tad more unstable, so feel free to tie it down and try some light-stress training techniques for best results!

Keep in mind: One of the main issues of the DFT system is that the roots don’t get properly aerated, making this system a lot harder to grow plants which rely on it for rapid growth, such as cannabis. This can be avoided by introducing an airstone into the sloped container, and this may help to a certain degree, but it still isn’t very optimal compared to DWC and ebb and flow systems.

Wick Systems

How it works: Wick systems are probably the simplest hydroponic system out there. They rely on a set of wicks to feed the plant nutrients, which is where they get their name from. In a hydroponic setup with wicks, plants are suspended in net pots filled with a growing medium such as clay pebbles over a container of water mixed with nutrients.

A wick is attached to the net pots and lowered into the water container. As the wick absorbs the water and nutrients, roots will form around and attach to the wick at several different points to feed off the nutrients in the wick. This process is called capillary feeding.

Keep in mind: Wicks can be made from simple cotton material, but soaked cotton can easily catch mold if left unchecked for longer periods of time. If mold does appear, just replace the wicks where mold caught on and keep an open eye in the next few days for more. Be careful while detaching the roots which are connected to the wick, but be aware that some tearing is expected. As long as the main parts of the root are fine, the plant will survive.

Common hydroponic equipment

Aside from using water and nutrients to feed the plants, most systems also use a combination of external equipment. Some of the most commonly used pieces of hydroponic equipment are:

  1. Water pumps
  2. Air pumps
  3. Air stones
  4. pH adjusters
  5. pH & PPM Meter
  6. Tubing, valves, and fittings

Water pumps are the backbone of every hydroponic system which relies on having the water flow through the system. Certain hydroponic systems don’t have pumps, as the water in these systems is static.

Air pumps and air stones are introduced to systems which don’t give their roots enough “breathing room” on their own so they have to be supplemented with oxygen.

As their name indicates, pH adjusters are used to balance the pH value of your nutrient solution so it doesn’t burn out your plants. It’s also good to keep a pH tester around as well if you’re not too sure about the quality of your nutrients and water.

You should also keep around a PPM or EC meter, which measures the concentration of nutrients in the water. If the concentration is too high, your plants might experience nutrient burns. On the other hand, if it’s too low - your plants might not grow up to their full potential.

Let’s take a look at some of the best pumps, air stones and pH adjusters that will optimize and freshen up your setup!

Water pumps for hydroponics

Active Aqua is a hydroponic equipment brand that has a very good selection of water pumps for hydroponics. Two main things to keep in mind when buying a water pump are the flow rate and the size of the inlet.

The flow rate represents the amount of water a pump can pump out. If you plan on having a big system with lots of plants you’re going to need a pump with a high flow rate. For a small indoor system you should look at pumps which have a flow rate of 15-50 liters per minute, or 250-1000 gallons per hour (GPH).

Air pumps and stones

Air pumps are used to pump air into the plant roots in hydroponic systems through air stones. Depending on how many air stones you want to place in your system, you may need a bigger air pump with several slots.

Active Aqua also offers a variety of cheap air pumps. They have an adjustable airflow, they run pretty quiet compared to others in that price range, and they consume very little power.

pH adjusters

As we mentioned before, pH values play a big role in the health of your plants since the roots spend lots of time soaked in the water from which they feed. Even a slight imbalance in the pH values can seriously disturb your plant’s feeding, which is why to keep a pH tester around at all times.

There are lots of reputable testers out there, but we’d like to point out Bluelab instruments and GroStar instruments as some of the most reliable tools in the shed.

If you happen to run into issues with your pH values - they may be too acidic or too alkaline, you can reduce and raise the pH value of your nutrient solution with Tnb Naturals adjuster. They come in two versions - Tnb UP and Tnb DOWN.

They are really easy to use, just mix the appropriate amount and pour it into your nutrient solution. Another great reason to use Tnb products is that they are created with all-natural ingredients and contain no harmful chemicals.

Tubing, valves and fittings

These three are a necessity for most hydroponic systems. Drip systems are the heaviest users of tubing, valves and fittings, but other systems such as aeroponics also rely on them to deliver water to the plants.

It is never a good idea to try and cut costs on tubing and such, since a leaky valve or cracked tube can be hard to spot, and by the time you’ve noticed it it may be too late for your plant.

Getting a well-made pipe system such as FloraFlex will make your life significantly easier as you won’t have to worry about any such issues popping up for a while.