What is Hydroponics?
Basically, growing plants without the use of a traditional dirt medium and using a nutrient rich water solution. Those mediums range from fiberglass to sand and from fired clay balls to nothing at all. Several branches of hydroponics include aeroponics (using air as the grow medium), aquaponics etc.
Deep Water Culture (DWC): What is it and how to get started
Info credit: Epic Gardening
If you’re new to growing plants hydroponically, words like “Deep Water Culture” can sound like they’re straight out of a science-fiction movie. Compared to soil gardening, hydroponics looks more complex – but it’s really not!
The different ways of hydroponic gardening (nutrient film technique, deep water culture, ebb and flow) might sound confusing, but once you break it down and understand what’s going on, it’s deceptively simple.
We’ll take a look at one of the simplest and most popular methods of hydroponic gardening today – Deep Water Culture, or DWC.
What is DWC?
Before we get into the nitty gritty details, let’s look at DWC from a high-level. In a DWC system, a plant’s roots are suspended in a well-oxygenated solution composed of water and nutrients. There are three critical parts of this solution:
- Oxygen: Because the roots are submerged in water and not soil (which has gaps and holes where air resides), the water needs to be well oxygenated so the plant doesn’t drown.
- Water: Think of this system as if you’re growing in soil and permanently watering your plants – this is one of the reasons growing hydroponically is so beneficial – you never need to ‘water’ again.
- Nutrients: A good quality soil contains all of the micro and macro nutrients that a plant needs to survive and thrive. Because we have no soil, we need to supplement the oxygen-rich water with nutrients so our plants can grow.
This method is called Deep Water Culture for two reasons. One, you typically grow with a reservoir that can hold a decent amount of water. More water means more stability in your nutrient solution, which means less monitoring and maintenance for you!
The second reason is because of how much of the root mass you submerge in the water. With other methods, the root mass of your plant might be exposed to the air and be drenched in water only a few times a day – ebb and flow is a good example of this. In DWC, your entire root system is submerged 24/7 – hence the name!
Benefits of DWC
There are a bunch of different ways you can grow plants hydroponically – DWC is just one approach. It’s a very popular one for many reasons, some of which are:
- Very low maintenance once you set it up
- Extremely fast growing time compared to soil (I’ve grown lettuce to harvest in 30 days instead of 60 in soil)
- Very little moving parts and assembly
Downsides of DWC
- In small systems, pH, water level, and nutrient concentration may fluctuate wildly
- In small systems, opportunity to over or under calibrate is VERY easy due to small scale
The Traditional Method:
The traditional method is the simplest way that you can build a Deep Water Culture system. They’re usually built with the following:
The method is simple: connect the pump to the tubing, the tubing to the airstone, and place the airstone in the bucket. Fill up the bucket with water, properly pH and add your nutrients, and start your seeds.Once your plants start to germinate and the roots start to hit the water, you’ll see an explosion of growth. Instead of spending energy growing the roots to search for pockets of water in soil, your plants can simply suck up as much water and nutrients as they need right away.
If the water is properly oxygenated, there’s no reason why your plant’s roots can’t remain submerged deep in the water (hence the name) for the entire life cycle of the plant!
Why It Works
Because of the highly oxygenated and nutrient-rich solution, plants grown in a traditional DWC system can be harvested up to twice as fast as normal soil-grown plants! I’ve personally harvested a head of lettuce in 30 days from germination. The fastest I’ve ever grown lettuce in soil is DOUBLE that.
The traditional method is amazing for beginners, but what if you want to scale your system to the next level? Most people move to a RDWC, or Recirculating Deep Water Culture system when they want to upgrade their garden.
If you’re looking to grow at scale, the last thing you want to do is have 10 individual buckets, all requiring their own calibration and adjustment. If you’re growing the same plant across 10 different buckets, doesn’t it make a lot of sense to have one main reservoir and feed that nutrient solution across all 10 buckets?
If you said yes…you just invented the RDWC system! Here’s an example:
you might be wondering how the oxygenation of the water occurs if you have multiple buckets chained together. Just as it would be inefficient to have separate nutrient solutions for each bucket, it’s also inefficient to run an airstone system for each bucket.
This is where the recirculating part of the name comes into play. As water moves from bucket to bucket, it’s shuttled around via spray nozzles that oxygenate the water.
The beauty of this modification to the classic DWC system is that you only have to calibrate, oxygenate, and add more water from one central location and it gets fed out to all buckets immediately. The best analogy here is the power grid: we don’t run our own generators in our homes. Power is generated from centralized locations and then ‘sent out’ through the power grid to our houses.
Although many people don’t consider Bubbleponics to be all that different that the traditional DWC, I personally think that it has a few advantages and is important enough to talk about. Despite its silly name, the adaptation that Bubbleponics makes is simple.
Instead of waiting for your plants to germinate and the roots to hit the top of the water in your reservoir, Bubbleponics aims to speed up that process by top-feeding the nutrient solution to your plants for the first few weeks.
All that’s going on here is the addition of a water pump to the system, with drip lines running up out of the tank to the net pots that your plants are sitting in. Simple, but very effective in speeding up the germination and seedling phase of a plant’s life cycle.
What Type of Growing Medium Should I use?
What Should I feed my Plants in a Hydroponic System?
Because we are growing plants without soil, we miss out on a good deal of nutrients that soil contains. When mixed with water, hydroponic nutrients are designed to replace all of the macro and micro nutrients found within soil. So, exactly what makes up a bottle of nutrients?
The first thing you’ll notice when you browse through bottles of nutrients are three numbers printed on the front of every bottle. This is known as the N-P-K ratio, or Nitrogen/Phosphorus/Potassium ratio.
The NPK ratio tells you exactly how much of each macro nutrient the bottle contains. If a bottle says 9-9-9, this means that the solution contains 9% Nitrogen, 9% Phosphorus, and 9% Potassium. You might have noticed that this adds up to 27% – what’s in the other 73%? Typically, water, micro nutrients and other chelating agents make up the rest of the solution.
The NPK ratio will differ depending on what phase of growth the plant is in – but we’ll get to that later. First, let’s talk about what these different macro nutrients do for a plant’s growth.
Nitrogen, Phosphorus, Potassium. These three nutrients are absorbed in the largest quantities by plants and are known as macro nutrients. They serve absolutely vital roles in a plant’s development. Here’s what each of them do:
Nitrogen – Necessary for the formation of amino acids, co-enzymes, and chlorophyll.
Phosphorus – Sugar, phosphate and energy production. Helps to produce flowers and fruits, as well as stimulates root growth.
Potassium – High levels of this element are required for protein synthesis. Helps to manufacture sugars and starches, as well as contributes to root growth and plant hardiness.
Without these macro nutrients, a plant could not survive. Plants need different amounts of these macros in different stages of their lives. An excess or deficiency of any of these nutrients can be devastating to a plant’s development.
Plants need more than the three macro nutrients to thrive. The following nine elements are known asmicro nutrients, and are required in smaller quantities for a healthy plant.
Boron – Combined with Calcium, helps to form cell walls.
Calcium – Combined with Boron, helps to form cell walls.
Copper – Activates enzymes and is required for respiration and photosynthesis.
Iron – Used to form chlorophyll and in respiration of sugars for energy.
Magnesium – Catalyzes the growth process and makes oxygen during photosynthesis.
Sulfur – Synthesizes protein, helps with fruiting, seeding and water uptake. Also acts as an organic fungicide.
Zinc – Helps to form chlorophyll, along with assisting respiration and nitrogen metabolism.
Types of Hydroponic Nutrients
Nutrients typically come in two different varieties – powdered and liquid. The powdered variety is generally harder to work with. It won’t dissolve fully into water and oftentimes doesn’t have added pH buffers. Liquid varieties are much more popular and easy to use. They come highly concentrated, so it’s important not to spill any on your body or your plants. Other than that, they’re fairly easy to use. All you need to do is mix them thoroughly into water at the desired concentration, and you’re set. Most of them come with pH buffers, which means that you don’t have to balance the pH of your water yourself – the nutrients do it for you.
What should my pH be at, and how do I check it?
In a hydroponic setup, you will almost always be using liquid or powder nutrients, so save yourself a ton of trouble by watching and adjusting the pH as needed! The pH will naturally change over time, and you only need to correct it when it starts going out of the 5.5-6.5 range.
What kind of lighting do I need for my Hydro Grow?
When choosing an HID system the first thing to take into consideration is the area you want the lighting fixture to illuminate. Based upon this you can choose from several different wattage systems; 1000, 600, and 400 watts are the most common. A 1000 watt system will cover about a 5 x 5 ft area, a 600 about a 4 x 4, and a 400 will cover an area of about 3.5 x 3.5 ft.
How to Keep Your Hydroponic Reservoir Cool
One of the more annoying problems we deal with as hydroponic growers is keeping an oxygenated root zone at the perfect water temperature. It’s crucial to squeeze as much yield out of our plants as possible and minimize the potential of disease and infection. However, keeping your hydroponic reservoir cool can be a challenge.
Why Do Roots Need Cool Temperatures?
Most indoor hydroponic growers that use a deep water culture system will run into the reservoir temperature issue at some point in a grow. DWC systems tend to heat up quick when under high wattage HID lighting.
This bumps up the temperature of the nutrient reservoir, which increases the temperature around the root zone. Because of this, the amount of dissolved oxygen in the root zone is lowered. When you combine these factors with plants growing faster in a hydroponic environment, you’ve created the perfect storm for oxygen deprivation. And when that happens…you open yourself and your grow up to pathogens like pyrethrum.
or best results, you want your air temperature to be higher than your water temperature. Typical ranges are 75-80F (23.9-26.7C) for air temperature, and 68F (20C) or lower for water temperature.
Even though roots grow better at the slightly higher temperatures of 70-75F (21.1-23.9C), you would be inviting in pathogens and root diseases that thrive at these temperatures as well. Keeping yourself and your roots safe means operating under 68F.
So, How Do I Cool My Hydroponic Reservoir?
There are a variety of good ways to cool down your reservoir, ranging both in price and how annoying they are to deal with on a daily basis.
Regardless of the method you choose, you have to ramp up your cooling efforts in the warm summer months – especially if you use a deep water culture or small-reservoir system (the small reservoir size heats up faster).
Buy a Chiller
The most effective (and most expensive) method is to buy a water chiller. These are electric units similar to air conditioning units that are made for operating underwater. They’re basically composed of fans, compressor coils, and a refrigeration line.
All you do is plug and play with these bad boys. To cool water even quicker, make sure you’re circulating your nutrient mixture.
Most commercial growers will use a 1.5-2 horsepower chiller to handle most of the cooling responsibilities and then manage the rest on a case by case basis.
Paint Your Reservoir
Darker colors absorb more heat. If your reservoir is made of a dark plastic, consider painting it a lighter color – preferably white – to reflect some heat. Using something as simple as white spray paint can do the job and knock a couple degrees off of your reservoir temperatures.
Keep It In The Shade
This is a really obvious tip, but I feel like I had to mention it. If you can minimize the amount of light hitting the reservoir itself, you’ll be minimizing the amount of heat that is transferred to your nutrient solution. Keep it in a shady area of block the surface with cardboard or aluminum foil.
Increase The Size Of Your Reservoir
Many hobby hydroponic growers use smaller reservoirs which are exceptionally prone to temperature fluctuation. By building or buying a larger nutrient reservoir like this 75-gallon monster, you can add some stability to your temperature without building or buying any other cooling materials.
As an added bonus, your pH and ppm will remain more stable as well due to the larger volume of water.
Top Off Your Solution
An elegant solution is to simply add cooler nutrient solution to balance out the temperature in the reservoir. This isn’t a solution you can use all of the time, because chances are high that if you have a temperature issue, it’s a persistent one. Just use this as a spot-fix if you have a one-time temperature fluctuation.
Note: If you add cooler nutrient solution quickly, the drastic temperature change could shock your roots.
Bury Your Reservoir in The Ground
If you’re growing outside, you can dig out the ground and bury your reservoir. The cool, dark environment below the surface of the soil will keep the reservoir exceptionally cool. You’ll almost never go into danger zone temperatures in the root zone if you use this method – but it does require a lot of effort.
Make a Swamp Cooler
A swamp cooler is a pretty ingenious cooling method – I didn’t know about it until I did some research. If you take a simple clip-on fan and blow it across the top of the reservoir, you will see incredible temperature drops. You can expect a 5-10F decrease in temperature…but at a cost.
Usually you’ll need to top up your reservoir more often, because swamp coolers are utilizing evaporate cooling (meaning you’re losing water to the air). If you think about this deeper, this also means that your ppm will increase due to evaporation…so be careful if you use this technique.