DIY Hydroponic Guide : Kent Chilli Garden

DIY Hydroponic Guide

This guide shows you step by step how to build your own Deep Water Culture (DWC) or bubbler system. We chose this system for the first hydroponic guide, because it is the simplest and cheapest system for the novice to get to grips with.

How does this system work?
A DWC system has the plants roots suspended permanently in a nutrient solution – this provides food and water, but blocks air getting to the roots. Plant roots need oxygen. To overcome this, the nutrient solution is aerated with an electric air pump and air distributor of some kind, most commonly an aquarium type airstone. This helps to stop the solution stagnating, and supplies a high level of oxygen into the solution and therefore to the roots of your plant.

There are two main types of DWC system – independent single pots, and multiple pot interconnected systems which also have a reservoir and “brain tank”. Each system has it’s own benefits and drawbacks;

A multi-pot system has one reservoir tank to mix nutrient solution in, and one drain point, making it much more time effective when servicing lots of pots. It also means that tiny variations in nutrient levels have less effect, due to the larger volume of water. They are however much more expensive to set up, take up more space, and if you have a problem with one plant ( such as Pythium or “root rot” ) then it can spread quickly to all your other plants.

A single pot system is very cheap to set up, and is excellent if you are new to hydroponics and want to experiment with a few pots using different nutrient types or concentrations. If you have a problem with a plant, it stays isolated from your other pots. On the downside each pot has to be managed separately, taking more time, and the relatively low water volume means you have to get your nutrient measures spot on.

Choosing which depends on your budget, how much time you have to manage them, and how many pots you want. Personally I wouldn’t want to run any more than about half a dozen as independent pots, but it’s a personal choice. As this in intended as a beginners guide, we’ll be building the cheaper and easier single pot type.

In it’s most basic form, it consists of a bucket, an air pump, an open basket type pot for your plant, and… that’s it! How complicated can this be…?

Here’s a list of things you will need;

Bucket with lid
Net pot
13mm flexible pipe
13mm inline valve
13mm sealing gland
4mm barbed elbow
4mm flexible pipe
M16 x 1.5 sealing gland
Air pump
Airstone
4mm clear airline

And some tools;

Drill
6mm drill bit
13mm drill bit
25mm drill bit
Adjustable hole cutter bit (or sharp craft / carpet knife and steady hand)
Adjustable spanner
>Scissors
Tape measure

Let’s start with the bucket. Get a large strong one – we use these 20 litre ones.

It is important that they completely block out light getting inside them to prevent algae building up in the nutrient solution. It’ll need a sturdy lightproof lid too.

Now you could simply drop an airstone in the bucket and put your plant in the top and it would work, but to make maintaining the system easier a little work here will save lots of problems later. Bear in mind that you will need to regularly top up, and completely change, the nutrient solution in the bucket. Having to take out your plant so you can empty the bucket is awkward, and potentially damaging for the plant – especially if it grows into a hydroponic monster! To overcome this we will fit a drain tap to the system. But how do we know if it needs topping up? A level indicator is a great way of getting an instant check on how much solution is in there, so we’ll fit one of those too.

So, we need to drill two holes in the bucket, one for each. For the drain tap, we need to drill a 25mm hole near the bottom of the bucket to accommodate our 13mm sealing gland. It needs to be as close to the bottom as possible for maximum darinage, but leave enough room for the gland to seal properly.


I mark the centre of the hole 23mm from the bottom of the bucket, which gives plenty of space. We will also need a hole for our level indicator. It doesn’t need to be right at the bottom (if your nutrient is that low you’ve got bigger problems) – so for neatness I fit in horizontally in line with the centre of the drain tap, a few cms off to one side so it’s on the front and easily visible. For this you’ll need to drill a 13mm hole.

With both holes drilled, use a sharp craft knife or some sandpaper to smooth any burrs or sharp edges, and you’re ready to fit the glands. But we’ll do that in a minute, let’s get all the cutting and drilling out of the way first.


The lid of the bucket will need a few holes in it, the biggest one is for the net pot. The net pot itself doesn’t need to be too big, remember that the roots will grow through it into the nutrient solution.


We use these 14cm net pots, which are sturdy enough to support the weight of a fully grown plant. To fit them into the lid of the bucket, you’ll need to cut a hole in the centre of the lid with a diameter of 135mm. If you’re lucky and have an adjustable hole cutter then great! If not, it’s easy enough to cut out by hand.

 

 

 

If you don’t have a compass you can simply turn the pot upside down on the lid and draw around it. Then, so that the lip of the pot has enough lid to sit on, draw another circle 5mm inside the hole you drew around the net pot. Now using a sharp craft or carpet knife, cut out the smaller hole.

 

Your net pot will now sit neatly in the cut out.

There are another couple of holes we need to cut into the lid. The first is for the airline – this will need to be a 6mm hole, drill it off to one side so you can pass the airline down the inside edge of the bucket. The other hole you will use for filling the bucket and checking temperature / pH / ec levels (more on this later). It doesn’t need to be a large hole, but big enough to access the solution with whatever testing gear you have, and to accommodate a funnel to fill it up. I drill a 25 mm hole. Make sure you keep something aside (like a bit of the black plastic you cut out for the net pot) to put on top of this hole to keep the light out of the solution.

We’re now done with all the drilling.

 

 

So, let’s get back to the drain tap and level indicator.

To fit the drain tap, remove the back nut and one of the washers from the 13mm gland, and fit the threaded section through the 25mm hole. Refit the washer (you should now have a washer directly on either side of the hole) and fit and tighten the nut – initially by hand, then half a turn with a spanner (I turn the nut on the outside of the bucket with the spanner, it’s easier to reach). That should form a strong watertight seal.

Do the same with the smaller sealing gland, and it should look something like this.

You’re ready to fit the bits on the outside.

 

 

 

 

 

 

To make the drain tap assembly, you’ll need your 13mm inline valve and the 13mm flexible pipe. It’s simply a matter of cutting the pipe to the length you require, and fitting the valve inline wherever it best suits you. I use scissors to cut a 100mm length of pipe and fit it into the sealing gland. To do this remove the outer nut from the gland completely and fit it over the pipe. Now slide the pipe into the gland, through what will be a fairly tight fitting rubber sealing washer. Push the pipe through until it is flush with the inside nut, and tighten the outer nut by hand to form a seal around the pipe.



The inline valve will now form a push fit seal onto the pipe, and you can add however much pipe you need to the other side of the valve to make draining easier.

Now for the level indicator.

Cut a length of aprox 80mm of the black 4mm flexible pipe, and fit it to one half of your 4mm elbow. This is the section that will fit through the sealing gland. Note that you can’t use the clear airline for this bit as it is a bit too soft, and in my experience doesn’t form a reliable seal. On the other side of the elbow fit the clear airline. The length will depend on the height of your bucket – you want it to go higher than the water level obviously, but I take mine up so it sits under the lip of the bucket – so for these it’s 280mm long. Now fit the black tube through the sealing gland the same way you did the drain tap, making sure that the elbow is pointing up. You can trim any excess off the inside of the bucket if you need to. Now you will need to fit the level indicator to the side of the bucket – you can use tape, glue, whatever you like really. I use tape – one strip at the bottom, and one near the top. I use this one as a marker also, and place it level with the bottom of the net pot. The very top of the clear pipe I tuck under the lip of the bucket and secure it with silicon sealant. Make sure though that the end of the pipe is open to the air, if it’s blocked the air pressure in it will not allow water into the pipe making it useless as a level indicator!

Now, this isn’t the most elegant solution, particularly as the sealing gland protrudes away from the bucket so much. It is however secure, reliable, and easy to fit. You could use tophat grommets as a sealing solution instead of glands, but I don’t like them. They’re not as reliable, and often need “help” in the form of silicon sealant (which doesn’t adhere to these plastics very well) although in fairness aren’t designed for the thin walled buckets we are using.

 

 

 

 

 

We’re almost ready to go. Now is a good time to test for leaks, so fill the bucket and leave it overnight somewhere safe you can check if it’s leaking. In the bath is a good idea, just in case… but of course it’s fine!

So, the last thing left to do is fit the airstone and pump and put it all together. Using these aquarium type airstones has a couple of benefits over just putting the airline straight into the water. Firstly it weighs it down to the bottom of the bucket, but most importantly it makes a few big bubbles from the airline into hundreds of very small bubbles. This gives a much greater surface area, meaning that more oxygen will dissolve into the water.

We selected a 5 inch airstone, coupled to a Hailea AC9610 adjustable pump – this model has 4 outlets and will easily run 4 of these buckets, but a smaller single outlet pump will do fine for a single pot. It’s worth getting a decent reliable pump, because if this fails, so will your plants! One thing to keep in mind though – these pumps are talked up in their write ups as being very quiet – in fact the model we use here is called a “super silent” pump. It’s not. They lied! So, don’t put this in the bedroom or near the TV!

 

 

 

As for how much air is needed, the solution should look like it’s boiling. That way there are lots of bubbles in the solution and popping on the surface, and it helps to agitate the solution slightly.  

 

 

 

Now we’re pretty much ready to go, but how to run it…? Here are a few things to think about.

Where to put it?
Obviously light will be a consideration, but we will talk about lighting in another guide.
Physically the bucket needs to be high enough to that you can get another bucket the same size underneath it to drain it into.
Ideally the air pump should be above the water level, so if it does fail the water doesn’t drain back into the pump. You can use a non-return valve if you can’t, but I’d rather have the pump up high.
You will also need to site it somewhere you will be able to support the plant with a hanging cable or net of some sort. We’ll get onto growing media in a while, but this will not provide a strong enough base for the plant to support itself and it will need help.

How much solution to put in it?
The level should be no higher than about 25mm below the bottom of the net pot, allowing the roots to grow down into it. Never allow the stem of the plant to become waterlogged. The bubbles bursting on the surface will help to keep the growing media moist, but to begin with you can hand water the plants from the top until the root growth is sufficient. We simply drain a little of the solution, check the pH levels, and pour it back into the bucket, watering the plant at the same time.
With these 20 litre buckets and pots, the ideal level is 12 litres of solution, which we mark on the level indicator.

Ok, but what nutrients to use?
There are many nutrients available now for the hydro market, but whatever you use make sure it is specifically designed for hydro use. Much the same as our soil grown plants, we find that the HESI range is particularly good quality, and is easy to use. Please take a look at the HESI homepage using the link below for detailed prodct info.
To get you started, you’ll need something like this.

HESI Fertiliser Homepage

The 2 white bottles are pH plus and pH minus (growth). HESI are to our knowledge the only company clever enough to separate their pH control products into growth and bloom phases. pH minus is essentially acid, and every other pH minus product we’ve been able to find has been phosphoric acid – but phosphorous is a nutrient in the bloom phase, so will mess up your nutrient levels in the growth phase. The HESI pH minus growth product is nitric acid – nitrogen being the main nutrient in the growth phase. Their pH minus for the bloom phase it phosphoric acid. Clever blighters eh!

As for how much to use, that’ll be for you to experiment with. There are lots of forums right across the internet about growing with hydroponics. Most of the ones I’ve found seem to be cannabis growers (I certainly wouldn't advise you try this in the UK...) but all the same there are some very knowledgeable and experienced growers out there, so take some time to look around and get the benefit from different people’s experience and knowledge. But to coin my favourite phrase when it comes to nutrients for chillies, less is more! It’s very easy to do a lot of damage to your plants very quickly with too high a concentration of nutrients, especially with DWC. Start low and work up. As a guide, we start our young plants in a solution that is 1/8th of the strength of the HESI Hydro grow schedule. Yes, an 1/8th! Just bear in mind that while the HESI Hydro grow schedule is dedicated to their products, it isn’t necessarily designed specifically for DWC or chilli plants. We find these levels work nicely for young plants (those that have just got their 3rd set of leaves) and we slowly build it up from there as they get stronger and acclimatise. If you’re not convinced, here is what happened to a plant in only 12 hours in a half strength solution.

See our nutrient schedule here. Less is more…

What to put the plant in?
There are a few different growing media suitable for hydroponics, so take your pick. Personally I think clay pebbles are the best option. They don’t get waterlogged like rockwool can, and are easier to keep clean. Just make sure you do clean them thoroughly before you use them, as they will be very dusty. Once rinsed, it’s advisable to soak them in a solution of around 5.5 - 6 pH to make sure that they won’t adversely affect your levels once the system is running. Once clean they are pH neutral.

You’ve mentioned pH, EC and nutrient levels and measuring them… what are they?
The EC (electrical conductivity) of your solution is an indication of the nutrient concentration. The higher the salt level, the higher the ec. It is only an indication however, it will not tell you what ratio of which nutrients are present, so while it can be a useful monitoring indicator it cannot be relied on alone.
It can be measured in different ways – ppm (parts per million) or ms or µs (milli or micro Siemens). The SI unit is S/m, but most meters will measure in µs/cm. Our advice is to get a reliable meter and get to know what and how it measures. For example, measure your tap water first. Then add a level of nutrient, and measure again. Add a different nutrient, measure, combine nutrients, measure… you get the picture. Sometimes a lower ec can result in a higher intake of water into a plant's tissue which, in turn speeds plant metabolism and increases nutrient transport, especially in young plants. Less is more… just thought I’d mention that.

The acidity of the solution of measured in pH (“power of Hydrogen” or “potential Hydrogen”) and is measured on a scale on 0-14, with 0 being highly acid, 14 being highly alkali, and 7 being neutral. Chilli plants do best at a slightly acidic pH 6. To be more exact, pH 6-6.3 for vegetative growth, 5.7-5.9 for flowering and fruiting. 6 will do fine. If you only get one measuring tool for your hydro grow, a pH tester is the most critical bit of kit. Very strong solutions at either end of the scale will damage your plants, and slightly less extreme “off target” levels can mean that the nutrients in your solution cannot be used by the plant. Adjust your solution using as little of the pH minus and plus products as you can get away with, generally adding drops at a time. You may find that you struggle to get this right to begin with, as the pH will not seem to move much then it will suddenly shoot off. Keep a daily monitor of your pH levels until you are familiar with your setup.

While we’re on the subject of measuring, temperature is another thing to keep an eye on. The temperature of your nutrient solution is quite critical. If it drops to 15 centigrade your plants metabolism will slow. Anything over 21 degrees and the amount of oxygen the solution will be able to absorb will reduce. This can be a problem in the summer, especially with black buckets, so a coating of foil is a good way of reflecting heat.

How often does the solution need to be changed?
This depends on the size of your plant and how much it is absorbing. You can top up the solution for plants that use a lot of liquid, using either plain water or a lower strength solution, but I’d recommend changing the solution completely every 14 days or so. Simply drop out the old solution through the tap, mix a new batch and fill it up again! Now you’ll notice that the drain tap location doesn’t allow all of the solution to drain from the bucket, leaving a litre or so in there. This isn’t ideal, but not a huge problem. I drain the system, then add 3 litres of plain water, and drain again – repeat this 3 times. This is far more effective at diluting contaminants in the remaining litre of solution than just adding 9 litres in one go. If there is 1 litre in the bucket, the 3x3 method will reduce the contaminants to 1.56% of the original level, compared to 10% when adding 9 litres in one go.

So there it is. You are now the proud owner of a DWC hydroponic system! Have fun with it and happy growing. And why not put the same plant type in a soil pot next to it and see the difference.

As always with our guides, we hope you found it useful. This one in particular is not meant to be an exhaustive guide (it’s long enough already!) and is designed for newcomers to the hydro world. But if anything is unclear, or you feel we have missed anything, please get in touch.

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