Lost in a sea of plastic trays …
I spotted them as soon as they came in through the door of the growshop. This couple weren’t just browsing. To me it was obvious that this was their first time in a hydroponics store. I watched them eye up the seemingly endless array of nutrients, additives, powders and other plant products. Then they spied the plastic trays stacked up next to the grow tents. They looked them up and down with evaluative frowns, and finally they continued to the pipettes, propagators, pumps, sheeting, ducting, fans, filters, lights, reflectors … well, you know … the whole shebang you see in any growshop really!
Eventually, they made their way to the counter looking a bit overwhelmed.
“I want to start growing hydroponic”, began the young gentleman.
“Well you’re in the right place!”, my chirpy salesman friend responded sipping a well brewed cup of coffee. The chap gestured a half spin around to glance at the store again and, turning back, asked a very simple question: “Where do I start?”
Q. What plants can be grown in a hydroponics system?
A. Anything that can be grown in soil can be grown hydroponically. Flowers, herbs, vegetables, fruit trees, and ornamental shrubs. You name it!
Where to start?
The hydroponics store can be a daunting place for a newcomer. With all the aforementioned peripheral products on show (often specific to growing indoors) the core simplicity of hydroponics can all too easily be lost.
So, for now, forget about growroom design. Forget about lights, fans, ducting, and all that. Hydroponics is none of these things. Hydroponics is simply growing without soil. If you want to start thinking about growing hydroponically, the logical place to start is by taking a look at the different types of hydroponic systems available. All hydroponic systems are trying to do the same thing. That is – to provide oxygen, water and nutrients to your plants’ roots, these (along with light) are the essential core elements that your plants need to grow and flourish. Whether you are growing indoors using supplementary lighting, or in a greenhouse, the science of hydroponics remains the same.
Fundamentally, hydroponics is very simple and there are lots of easy to use and affordable systems out there to help you achieve brilliant results.
Why different systems?
Why not? We don’t all drive the same car do we? All systems have their pros and cons. Some are small, good value for money and easy to use – but don’t permit much scope for fine tuning or up-scaling. Some systems are suited to particular applications (such as one or two large plants) whereas others can also adapt to growing larger numbers of small plants too. Some systems are more expensive and have plenty of scope for tweaking, but inherently there’s more potential for things to go wrong.
As well as asking yourself questions about the space you have available, make sure you ask yourself a few more of these practical questions:
- How much time will you have to spend with your plants?
- Will you often be leaving them unattended for more than a night or two?
- How confident are you in your own DIY abilities?
- How many flights of stairs would you have to haul 50 litre bags of growing medium up (if you were to choose a system which required it?)
- Does the space in which you want to grow suffer ever from extreme temperatures? (I’m thinking specifically of attics here)
- How much space do you have for a nutrient tank?
- How important is it for the system to operate quietly?
Hydroponics in a nutshell
The word “Hydroponics” comes from Greek, “hydro-ponos”. Literally it can be translated as “water (hydro) at work”. So what “work” is the water doing? Well, as it happens, quite a bit actually! Hydroponic plants are not grown in soil. Instead all the nutrients they need are supplied directly from the water. This is achieved by first dissolving special hydroponic nutrients into the water – the resulting “mix” is often referred to as a nutrient solution. It contains all the essential food in a directly accessible form – food which a plant would usually have to search for in soil by creating an extensive root system.
Hydroponics: Pros and Cons
The advantages of hydroponics include:
- Higher yields
- Increased growth rates
- More control over nutrient and water levels
- Maintenance involves less labour
- Soil borne diseases are virtually eliminated
- A sterile growing environment avoids soil borne pests
- While removing soil-grown crops from the ground effectively kills them, hydroponically grown crops such as lettuce can be packaged and sold while still alive, greatly increasing the length of freshness once purchased
- Fewer pesticides are required
- Edible crops are not contaminated with soil
- Water use can be substantially less than with outdoor irrigation of soil-grown crops
- Many hydroponic systems give the plants more nutrition while at the same time using less energy and space
- It provides the plant with balanced nutrition because the essential nutrients are dissolved into the water-soluble nutrient solution
Of course there are some down points:
- Higher set up cost than just buying some soil and pots although yield benefits make this worthwhile
- Less margin for error
- Recirculating hydroponic systems (those which pass the same nutrient solution over the roots more than once) can spread disease between plants. Nothing to do with hydro, I problem common will all growing
- If timers or electric pumps fail or the system clogs or springs a leak, it can spell disaster for your crop so it’s important not to buy the cheapest pumps and timers
How does hydroponics give higher yields?
Hydroponic growing media is lighter than soil so it allows roots more access to oxygen and a better flow of water and nutrients and all this helps to stimulate root growth. Plants with ample oxygen in the root system also absorb nutrients faster. The nutrients in a hydroponic system are mixed with the water and sent directly to the root system so the plant does not have to expend energy searching in the soil for the nutrients that it requires. The hydroponic plant requires very little energy to find and break down food. The plant can then invest this extra energy to grow faster and to produce more fruit.
Active vs. Passive
Before we talk about specific types of hydroponic systems, it’s useful to explain a few ‘core’ principles to help us distinguish between them.
You may have heard of “active” and “passive” systems.
An active hydroponic system is labour saving and automatically provides plants with water and nutrients much more frequently than is possible with manual feeding. Active hydroponic systems actively move the nutrient solution, typically using a pump. In active systems more nutrient solution is passed over the root-zone than the plants actually take up. Active hydroponics is a bit like dining at one of those conveyer belt sushi bars with those endless little nibbles going round and round. Lots more food is presented than you can actually eat! (Unless you’re a fat bastard.) You just take what you want when you need it, but the more frequently the roots have opportunity to take up nutrient solution the more nutrient solution they will be able to take up and the bigger the yields will be. The roots are able to take up much more nutrient solution than if they were manually fed just a few times per day – and this results in higher yields. In the last thirty years the technique has become the main commercial growing technique.
Q. What do you mean by “growth media”?
A. Growth media, growing media, medium, substrate … it’s all amounts to the same thing. Some hydroponic systems need a substitute for soil so that the plant has ‘something’ to actually grow in – to keep it sturdy for one thing – but also to absorb nutrients for the roots to take up.
Restrictive and non-restrictive growth media
In order for active hydroponics systems to work effectively, the flow of nutrients must not be restricted by overly absorbent growing media – otherwise things would get very soggy and oxygen starved. NFT uses very little medium – most commonly 3 or 4” cube but if you’ve got good plant support you can just use a 1” propagation cube. Coco fibre is a restrictive media. It absorbs nutrient solution into itself rather than letting most of it merely flow through it like clay pebbles.
Hydroponics at its simplest: Passive hydroponics using pots
With passive hydroponics the plants are grown without soil but the grower has to decide what quantity of water and nutrient and in what ratio the plants should be fed. The simplest example of passive hydroponics is hand-watering your plants in pots of coco fibre. This is the most basic way of growing hydroponically – ideal for beginners. If you don’t mind the added labour of watering your plants regularly, and you are happy to guess how much water and nutrients to feed your plants then it’s an attractive and cheap option, although yield increases won’t be anywhere near as large as in an active hydroponic system.
Water your plants little and often. Sit every pot in its own deep saucer. Once they are well established in their pots you can supply nutrients solution by watering the saucer, rather than the top of the pot. The growing medium will suck the nutrient solution upwards through capillary action and keep a moist, yet aerated environment around the roots. Remember, moisture, nutrients and air is the winning root-zone combination. A lot of growers feed their plants by watering from the top –this isn’t ideal for established plants.
The size of your pots should reflect the desired finishing size of your plants. A 3 – 5 litre pot is fine for a maturing a cutting that has had little or no vegetative growth since rooting. Whereas a 10 or 15 litre pot can accommodate a much larger plant that has enjoyed a lengthy vegetative period of four to six weeks or more. Obviously these are just ‘rules of thumb’. You will have to experiment for yourself with your own particular plants and varieties and see which works best for you.
Recirculate or run-to-waste?
As well as considering hydroponics systems as “active” or “passive”, they are often divided into two alternative categories: Recirculating and run-to-waste.
When a hydroponic system is described as “run-to-waste” it means that any excess nutrient solution that has drained from the root-zone is not used again. It is usually collected in a waste tank to be disposed of later. This means that the nutrient solution is only ever used once.
In recirculating systems (Ebb and Flow, NFT) any excess nutrient solution is fed back into the nutrient reservoir to be ‘recycled’. You will need to keep an eye on rising pH and nutrient strength in your reservoir as this will tend to fluctuate (over a period of time not straight away). Many growers top their reservoirs up with water every few days and adjust the pH back to optimum levels at the same time. The larger your nutrient reservoir, the less your susceptibility to changes in conductivity and pH. Depending on the size of the nutrient reservoir, it’s advisable to completely change its contents with freshly made nutrient solution every one or two weeks for most hobbyist applications -
Recirculating systems allow you to pass more nutrient solution over your roots because you don’t have to worry about waste. They use non-restrictive mediums (or no medium at all).
Let’s take a look at a popular type of recirculating system:
The Ebb and Flow System (aka Flood and Drain)
The Ebb and Flow system is particularly popular with growers who want to change feeding schedules throughout the plants lifecycle, especially those cultivating mother plants. It uses a submersible pump in the nutrient reservoir to pump nutrients into an upper tray containing the plants. The theory of “flood and drain” is very simple: When the pump is switched on, the nutrient solution is pumped up to the upper tray and it floods the root system, getting rid of any old air that was in the root-zone. Once the nutrient solution has reached the maximum level, it starts to drain back into the reservoir via an overflow pipe. As the nutrient solution drains back down into the reservoir, the root-zone takes in a fresh supply of oxygen rich air and stale air is pushed out.
More oxygen = increased metabolic rate = increased nutrient intake = more growth!
Clay pebbles are often used in ebb and flow systems. The tray is filled with pebbles and young plants grown up in rockwool cubes are inserted into the pebbles once roots start showing.
Some gardeners in the UK grow their plants in pots filled with coco coir and clay pebbles, or a mixture of small chunks of rockwool and clay pebbles, and sit these pots in the flood tray – the capillary action of the roots take up the nutrients they need in a similar way to the passive pot hydroponics method described earlier.
Active Ebb and Flow is a low maintenance hydroponics solution, which offers growers more control and great results are possible. Two key factors to get right are the automatic flood times and flood frequency.
When working out how long to flood for, remember the extra time it takes for the nutrients to drain back into the reservoir. Ideally, you won’t want to be using a standard 15 minute segmental timer to control your pump as fifteen minutes (plus drainage time) is too long for the root-zone to be without oxygen – a negative to basic ebb and floods. Obviously flood times will vary depending on the size and exact type of the system you are using, but as a general rule of thumb, once the nutrients have flooded to their maximum level (delimited by some form of overflow drainage mechanism that will be incorporated into the system) then it’s time to stop pumping. All good Ebb and Flow systems will come already supplied with the correct type of pump – one that allows the nutrient solution to drain back through it.
The required flood frequency will increase as your plants mature and their nutrient requirements increase. During the early stages, one flood a day might be sufficient. Whereas, towards the end of flowering period your plants may require four or more floods a day. Also, consider what medium you are using. How much does it absorb the nutrient solution? A restrictive medium like coco coir will need a lot fewer floods than clay pebbles, for example.
Ebb and flow moves a lot of water around. It may sound like an obvious thing to say but just make sure the reservoir is sturdy and fit for purpose. A couple of friends of mine were growing in an attic using a huge old second-hand nutrient tank which had two trays sat on top of it rather than one. They hadn’t noticed that it was already a little warped. During the flood cycle, the weight of top trays caused the tank below to crack and …… the rest of the story is very wet indeed…
Ebb and flow systems are not always based on a grow tray. Some ebb and flow systems work by connecting a series of special pots to a reservoir tank. (Often referred to as a ‘multipot’ system). The nutrient solution is pumped to each pot via a network of hosing. Each pot acts like its very own mini flood and drain system. Plants sit in an upper pot, which sits on a slightly larger lower pot. Nutrients are pumped into the lower pot – the base of the upper pot is perforated so that the plant roots can feed.
There are several different types of ‘multipot’ systems on the market. Consider the number and size of the plants you wish to grow and measure this against the size of the pots used by the system you are considering. In the early stages when your plants’ root systems are minimal, be sure that the flood height achieved by the system actually meets their roots. Otherwise, you can help things along a bit by hand watering for a few days. It’s also worth ensuring that your multipot system drains as well as it floods. Often it’s possible to make a few simple tweaks to optimise any given system for your particular environment – such as raising the plants up a few inches higher on a platform, so that gravity helps drain any run-off nutrients out of the pipe work and back into the reservoir.
Various systems are available as 4, 6, 12, 24, 36, or 48 pot systems.
Nutrient Film Technique (NFT)
The Nutrient Film Technique or NFT is also known as a ‘pure water culture’ technique insofar as the plants’ roots are not grown in any solid medium such as coco. Although saying that, many growers start their plants off in rockwool cubes, and then sit them within an NFT system. The roots are contained in a plastic trough or tube through which nutrient solution is constantly circulated.
NFT is probably the most popular hydroponic growing method in the UK with Nutriculture’s GroTank being the first commercially produced active hydroponic system on the market back in 1979. It produces huge yields by ensuring that the roots have constant – rather than just frequent – access to water, nutrients and oxygen.
As implied by the name, the depth of the nutrient stream is very shallow – just a couple of millimetres. This is to make sure that the roots have lots of access to oxygen.
So how do you create this “nutrient film”? Well, first of all the nutrients are pumped from the reservoir into the trough where the roots are sitting.
The bottom of the trough needs to be inclined at a very slight angle. Nutrient solution enters the trough at the top of the incline, and gravity pulls the nutrients along the trough. The run-off nutrient solution then re-enters the reservoir. Modern systems use special pumps which aerate the nutrient solution
NFT gives tremendous results. It is the arguably the easiest active hydroponic method to use because there are no watering schedules to calculate – once you are set up you just check pH levels and keep the tank topped-up. The plants just take what they need, when they need it and whatever they don’t need flows away so there is no chance of under-watering or over-watering – the biggest challenges facing growers.
It is important not to buy a cheap pump because if the pump fails plants can dry up quickly in an NFT system as there is no growing medium surrounding the roots to provide a fall-back, although the capillary matting provides some safeguard. One of the great things about NFT is the lack of growing medium, although this means there is less natural insulation around the roots to provide protection against extremes in temperature. So an NFT system with a thermostatically controlled heater is a good option.
NFT systems come in all shapes and sizes from 70cms long to a whopping 3metre long – there’s an NFT system for everyone.
Dripper Irrigation
A Recirculating Dripper System.
A dripper system can either be recirculating or run-to-waste. Nutrient solution is fed from the reservoir via a pump along some piping. This piping sometimes terminates in a “dipper ring” where it typically feeds one plant, or it splits off (usually via an adaptor) into several narrower pipes and into “dripper spikes” to feed multiple plants. These spikes are inserted into the growing medium by each plant site. Nutrient solution drips out of the dripper spike and into the growing medium. Adjustable dripper spikes allow you to individually adjust the drip rate to each plant. Any excess nutrient solution needs to be fed either back into the nutrient solution (recirculating) or to a waste point (run-to-waste).
Many active hydro drip irrigation systems offer the precision and control of hydroponic feeding combined with the flexibility of growing in pots.
Pots are placed on a support tray that rests on a nutrient tank and periodically nutrient solution is delivered to each plant through a dripper to each pot. So for those of you who prefer to grow in pots this method spares you the hours and hours needed to manually feed. If you don’t want to grow the number of plants supplied with a particular system you can simply remove some of the pots!
You can find systems in various sizes (4, 8, 10, 16, and 20 pot systems) – make sure you check that the dripper supplied are compatible with the media you want to grow in. Some manufacturers generous supply a range of drippers to suit different media.
Another great example of a self-contained recirculating dripper system is the Aquafarm and Waterfarm by General Hydroponics. Both systems work on the same principle – they differ only in size and price. Plants are grown within a chamber filled with clay pebbles. The growing chamber is suspended above a reservoir filled with nutrient-enriched water. An air pump drives the nutrient solution up through the “pumping column”, to the drip-ring, where it then drips down through clay pebbles. This infuses the nutrient with oxygen and constantly bathes the roots. .
Some growers increase the diameter of the drainage holes in the top pot first to allow the root systems more space!
Remember, as with all recirculating systems, keep an eye on rising CF and fluctuating pH and change the nutrient solution regularly.
Low pressure sprinkler / droplet systems
Amazingly, it’s possible to grow plants in air! Often these systems are referred to as ‘aeroponic’ because the plants are fed via a nutrient mist. The plants are secured (typically via net pots) at the top of the system and their roots dangle down into a lightproof box. Inside the box, a submersible pump is used to push the nutrient solution through atomisers, creating a mist. The idea is that the roots have increased oxygenation, of course, which speeds up growth.
As with NFT, there’s no media to speak of really – other than maybe something to start them off in. Great insofar as there’s not sack after sack of medium to dispose of afterwards – but remember to keep an eye on ambient temperatures.
High pressure fine mist systems (True aeroponics)
True aeroponics is achieved when plants are fed via a fine nutrient mist. High pressure and air compressors are used to create the optimum sized particles for liquid and oxygen feeding 100% of the time. In the past there have been problems creating this mist due to clogged atomisers. In the last issue of UGM we featured the Atomix – a British made true aeroponic system that has overcome these problems with state-of-the-art atomising technology.
Hopefully as well as expanding your knowledge on the types of hydroponic systems available, and the vocabulary that is used to describe them, you’ll be better able to make the right choice for your own particular circumstances. There are probably as many different ways to grow as there are growers! If you’re a beginner, my advice is keep things modest and simple from the offset – experiment with different ideas in your growroom and circle of friends. It’s not about saying which hydroponic system is the best – more, which one works best for you.
Well, that’ll do for now! We’ll be covering lots more systems in a whole lot more detail in future issues, as well as a few that we left out for brevity’s sake!
Thanks to UrbanGardenMagazine for the article Original Page Here
If you understand how hydroponic systems work–which is not difficult–you should have no problem building and maintaining the home unit I describe below. Most hydroponic systems employ some type of media, like rockwool, expanded clay pellets or perlite, to support plants and hold nutrient solution in their root zone between watering cycles. In medialess systems (often referred to as “water culture”), a continuous supply of nutrients is provided to plant roots either in a fine mist (aeroponics) or flow, in which the root tips hang (Nutrient Film or Flow Technique). A combination system, called aerohydroponics, employs both the flow of nutrient and the fine mist for the best of both worlds. Another water culture system is the float system, which many of you have probably read about in other articles I’ve written for The Growing EDGE. This type of system works by placing plants in a foam board so their roots hang through it, and floating the board so their roots hang through it, and floating the board on the surface of the nutrient solution in a tray or pan. There’s no doubt that all of these systems work very well, but they do have some drawbacks for home applications.
To make the stand, you can use regular Schedule 40 three-quarter-inch PVC pipe, and fittings to connect the pipes together. It is essential for you to create a one-inch slope from one end of the stand to the other for nutrient drainage to occur. The diagram below shows the construction of the stand and its slope for a single bed. You’ll want to build your stand according to how big your growing area is. My home system, as you can see in the photos, is a double-long bed. To start off, you may want to just make a system with only one growing bed (roof pan).
Once the stand is ready, the trays just get pop-riveted to it, using a silicone sealant to caulk around the rivets. Then you drill two half-inch holes in the lower end of each sloped tray and screw a male half-inch PVC adapter into each; don’t forget to caulk around them with silicone to protect against leaks. Connect equal lengths of half-inch PVC pipe to each adapter, using elbows and a T-fitting to create a cross-bar between the two that will join them into a single drain line to the nutrient tank, which should be situated directly beneath the drainage holes. Refer to the diagram below for a better idea of how this should look. In the systems I built, I fitted each of the drain holes in the end of the growing beds with a three-inch tube of window screening to prevent perlite from entering the nutrient tank.
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