All about Hydroponics
Welcome to Hydroponics
In the past we all had a garden and raised our own food. With our higher population density, traditional gardening in soil is not possible. But would it be possible (and sustainable) for a revival of everyone growing their own food using hydroponics. Most people have a spare corner in their house and most people could give upa few minutes of NCIS to do some planting, watering and harvesting. Think about it . . .
Types of systems
Stolen from this website Links to an external site..
We all know what plants look like in soil and how soil provides mechanical stability. Plants absorb nutrients from the soil mix or as irrigation additives poured onto the soil. Plant roots work against the mechanical resistance of soil and expend energy searching for nutrients and oxygen in the soil. Water in moist soil helps the roots expand and with the absorption process at the root surface.
Hydroponics comes in varying levels where soil is replaced with nutrient in-solution water. Plant roots can be flooded and drained on a cycle (also called ebb and flow), or in DWC hydroponics, permanently submerged in water (Deep Water Culture). Hydroponics offers the advantage of no energy wasted by roots searching for nutrients.
Aeroponic systems are a specialized version of hydroponics where the roots of the plant extend only in air and the roots are directly sprayed with a nutrient water mix (the recipe). The primary difference is the availability of oxygen to the roots. In hydroponics, one has to be sure to supply oxygenated water. Standing water gets depleted of oxygen over time. In aeroponics, oxygen is surrounding the roots at all times. Surplus oxygen accelerates nutrient absorption at the root surface.
Plant support in both aeroponics and hydroponics are provided by the hosting environment. Hydroponic plants tend to be stabilized with hydroton clay balls or coco-coir soil alternatives and flooded or submerged in water. Nutrients for hydroponics are provided in solution in the water. For aeroponics, the roots dangle directly in the air and the nutrient salts are mixed with water and sprayed as a vapor directly onto the roots. This completely eliminates mechanical resistance. Roots can grow and expand their surface area at will.
Oxygen Impact
Oxygen and moisture are key to the process of nutrient absorption in the cycle of photosynthesis. Nutrient salts move through the plant root surface along with water and oxygen to begin the conversion cycle. These nutrients are transported up into the canopy level, where photosynthesis uses light energy to convert CO2 and nutrient salts into plant growth, while releasing oxygen and water into the air. So the summary is roots need oxygen while the canopy needs carbon dioxide.
The difference in aeroponics vs. hydroponics vs. soil beyond the surplus of oxygen is control. Soil can be very forgiving. Plants in soil will grow naturally at a slow rate as roots extend their way through the soil. Soil can stay moist for extended periods of time as plants grow. Hydroponics and aeroponics accelerate this process by providing nutrients directly to the roots. Hydroponics has the downside that oxygen levels have to be managed over time. Standing water, depleted oxygen, pH levels, and nutrients can trigger algae growth and fungal problems in hydroponics. This requires steady attention. Hydroponic nutrient dosing is normally managed on a batch volumetric level. Everything is mixed at one time, irrigated, and when it runs out, mixed again. Managing nutrient dosage, water acidity levels (pH), and oxygen mix is a complex process in-solution. Providing the same nutrient levels to hydroponic plants across this cycle and a large irrigation area can be a challenge.
Aeroponics supercharges plant growth with a surplus of oxygen at the root surface. When this is combined with sensor technology and dynamic nutrient recipe dosing, plant growth is superior.
Aeroponic nutrient "dosing" can be precision optimized for nutrient dosage, spray time, light synchronization, growth phases, flowering, bloom, and fruiting cycles and pH levels, to maximize results. In a proper clean room environment, aeroponics delivers pure fresh results, with zero pesticides, highest quality flavors, and maximum growth.
Hydroponic Examples
There are many different types of systems in use. Here are just a few of the examples.
This first is a video (https://www.groshed.org/ Links to an external site.) is a small (8' x 10') "fish house" type of building that is super insulated. Notice there are no windows. Light is supplied ONLY by LEDs.
Here are some other growing systems:
This one is just about micro greens
Superior Fresh Links to an external site. is a aquaponics facility in Hixton Wisconsin. Really interesting and I think the future of food. This is not DIY but it has tons of information about large scale hydroponics and aquaponics. Check out how they start their seeds and then they are grown on "rafts" that travel the length of the greenhouse.
Here is an enclosed aeroponics system Links to an external site. for classrooms from Fork Farms. Really a cool idea. LIghts in the middle and hollow panels around it with the plantings.
Step by Step Hydroponics Links to an external site. is a great place to study the different factors in a system (David, glean the important things from this and capture on this website for students.)
A good explanation of the 6 basic types of hydroponic systems Links to an external site. (and sensors) from Sensorex. (pdf document)
System components
This next section is an overview of the critical elements of a hydroponics/aeroponics system.
All about Plants
What you want to grow may impact what type of system you build. Lettuce, microgreens, tomatoes, carrots? Each of these woudl have special system requirements. Figure out what you want to grow and then design your system for that plant. Best to start with something easy - lettuce. Here is a good factsheet on hydroponic tomatoes Links to an external site. by wikihow using an ebb and flow system.
Here is something on hydroponic strawberries Links to an external site. (also wikihow).
All about the Grow Structure
Plants need some physical structure. In soil gardens that structure is the soil. Roots in the soil provide a structure for the plant. With hydroponics there are several options to support the plants. There are tubes with holes for plant plugs (no media) and others that are more traditional with pots and non-soil media.
Will the plants grow in pots? How are the pots held? What holds the roots in the pots. How big will the plants get. How long will the roots be? How deep is the water to accommodate? These decisions are all a function of what plant you choose to grow.
There are many types of media: soil, coconut coir expanded clay, perlite, vermiculite perlite/vermiculite mix, nothing. Check this article Links to an external site.
All about Water
Components of a water system include a reservoir, a pump, piping, nozzle (aeroponics) and controls. Typically the systems are deep water culture with recirculation or ebb and flow systems. (Unless of course you are doing aeroponics). So the key to any system design is how to move the water in and out of the root area and control this circulation. Along with this might be the need for aeration. In all cases you will need a way to drain the system so you can refresh the nutrients.
Pumping. Most home system will use a very small aquarium pump. These are about 2.5 watts and pump 40 gallons per hour. When you select your pump remember the pump has to have enough pressure to overcome any elevation difference between the pump and the highest point of the water line. Some of these small pumps may only pump 2.5 or 3 feet high. This just means you have to think about the placement of your reservoir in relation to your plants. It is easy to go bigger with pump flows and pressure but this also means more power requirement.
Aeroponics systems are constantly running and dripping over the plant roots (or spraying over the plant roots)
Ebb and flow systems are cycling at least once per hour. Remember this cycling is needed to provide oxygen to the plan roots. This could be a constant pumping with a siphon system. (Bell siphon for draining video Mini Bell Siphon Experiment) Links to an external site.. The other option is just a drain tube installed in such a way to create a siphon.
Automatic controls using arduino are another option. This may be the case with the larger pumps that do not need to operate all the time.
All about Nutrients
The other important piece of the water system is the nutrients. This may be the trickiest thing about hydroponics. Most systems require some monitoring multiple times a week. This is for pH, Electrical conductivity as an indicator of nutrients. As you may have guessed, the plants are using the nutrients and the nutrients are being degraded in the water. This means replenishing the system.
The three main nutrients plants need in large quantities to grow are nitrogen, potassium, and phosphorus. However, plants require around 17 total nutrients in varying amounts to grow well. Plants in different stages of growth require different amounts of nutrients. Plants growing vegetatively (ie lettuce producing leaves, tomatoes growing before they start to produce fruit/flowers) need a lot more nitrogen, while plants in their reproductive stage of growth (producing flowers and fruits) need much higher rates of phosphorus and potassium. This means that if you are growing a plant for fruit, you’ll need to change the nutrient mix you use once the plant enters its reproductive growth phase.
Types of Nutrients
Nutrients are sold in various forms for field and hydroponic nutrient applications. Nitrogen is available in fertilizers as nitrate, nitrite, and ammonium. In soil, soil bacteria can convert ammonium into nitrate, which is then taken up by plants. However, in hydroponics, nitrates and nitrites are the best sources of nitrogen for plants, so make sure the nutrient mix you get has nitrogen that is at least 70% from nitrates or nitrites. This means you should not use a fertilizer intended for soil (which usually contains a lot of N in the form of ammonium) for a hydroponic system!
Selecting a nutrient mix - summary:
- Look for a mix with the words “water soluble” or “hydro” - this usually means the mix can be used in hydroponics. Do not use a fertilizer intended for soil application.
- Check that at least 70% of the N in the mix is from nitrate or nitrite, not ammonium.
- Choose a mix made for the correct stage of plant growth - for plants grown just for their leaves, only one mix will be needed. For plants grown for fruit or flowers, the nutrient mix will need to be switched from a high N mix to a high P and K mix when the plants start to produce flower buds.
How much nutrient mix is needed?
Different plants require different amounts of nutrients to grow, and these amounts can vary as plants grow. For some plants, like lettuce, the amount of N required stays relatively constant throughout plant growth, so the concentration of nutrient solution does not need to be changed. For other plants, like tomatoes and peppers, the amount of N required increases as the plant grows, so the nutrient concentration of the solution will need to be increased as the plants grow.
There are charts available to figure out what concentration of nutrients are needed as different types of plants grow. Nutrient mix concentrations are usually calculated based on nitrogen requirements, since nitrogen is frequently a limiting nutrient for growth. For a plant like lettuce, which requires a pretty constant amount of nutrients as it grows, a concentration of 120 ppm N in the nutrient solution is a good general amount to use, however, you can always do more research about your specific crop to figure out the optimal amount of nutrients at each growth stage.
Nutrient Mix Amount - Calculation
To calculate how much nutrient mix to add to your system, you’ll need to know how much water is in your system, how much nitrogen is in your nutrient mix, and what concentration of nitrogen your plants need.
For example, let’s say you have a 40 L nutrient solution reservoir, are using this nutrient mix Links to an external site., and are growing lettuce and other leafy greens, so you want a nitrogen concentration of 120 ppm. The nutrient mix says 10-5-14 on it, which means it is 10% N, 5% P2O5 (not 5% P!), and 14% K2O (not 14% K!).
Since 1 ppm N = 1 mg N/ 1 L water, you’ll need 120 mg N / L water, or 120 mg/L x 40 L = 4800 mg N total.
Since the nutrient mix is 10% N, you’ll need (4800 mg N) / (0.1 mg N/mg mix) = 48,000 mg = 48 g nutrient mix.
Adjusting & Changing Nutrient Solutions
The two main things people monitor in hydroponic systems are pH and electrical conductivity (EC). These are important because:
- pH: Nutrient availability to plants varies based on pH Links to an external site., so keeping a close to neutral pH (6.0-7.5 works well for most plants) is important so that the nutrients in the solution are actually available to the plants.
- EC: Electrical conductivity is a good measure of how many nutrients are left in the solution - a higher EC means that there are more nutrients left.
When should you change out your nutrient solution?
- When you are no longer able to keep the solution pH and EC stable with small adjustments, completely replace your nutrient solution with fresh solution (dump out your old solution on potted or garden plants!). This will probably be every 4-5 weeks.
- When a plant you are growing for fruit starts to make buds or flowers, and you are switching nutrient mixes, completely replace your nutrient solution.
All about Light
- How much light
- What kind of light
- How to measure
Before we get to crazy - watch this video. This is the kind of thing we really need to be thinking about.
Photosynthetically Active Radiation (PAR) are the wavelengths of light within the visible range of 400 to 700 nanometers (nm) that are critical for photosynthesis It so happens, this is the visible light spectrum. Note that the shorter wavelengths carry more energy than the longer wavelengths. PAR is typically measured as Photosynthetic Photon Flux Density (PPFD) which has units of μMol/m2/s. (micromoles per meter squared per second).
Light Video PAR, PPF, PPFD, and PFD Explained Links to an external site.by Dr. Bruce Bugbee
Light intro Links to an external site. from Al Gracian
Summary of Video lesson:
Pyranometer measures all short wave energy from the sun. (visible plus NIR) Wavelengths from 280 to 2800 nm. Measured in watts/m2. It drives transpiration but not photosynthesis.
PAR is between 400 and 700 nm but units were misunderstood. Started as watts/m2 but evolved to a flux density.
PPF photosynthetic photon flux. Units should be μMol/s but are sometimes shown that it includes area.
PPFD is a more accurate as it clearly indicates a flux density. [Technically flux is amount per time and flux density is amount/time/area μMol/s/m2. This is a light intensity.
Lux is a flux density and would have a direct conversion (divide by 50) to get to PPFD in μMol/s/m2
Lumens is a flux (total amount of light energy coming from a source)
Kelvin (K) - a measure of the light spectrum 2000 K is a yellow light (more red and yellow) 6500 K is a very white light - a more balanced light spectrum.
Lux to ppfd calculator Links to an external site.or Light conversion online calculator ppfd to xyz Links to an external site.Waveformlighting Links to an external site.
Which Wavelength is Best for Growing plants?
Turns out, most plants do well (best) with the full light spectrum (400-700) plus wavelengths from 700 to 760 (Far red). Red is the 640 to 680 nm wavelength. Some places will discuss the red to far-red ratio Links to an external site. as a critical parameter for plants. We don't do that in the makerspace - join a horticulture club!
Best case - LED or CFL's with the 5500 to 6500 K (K is Kelvin and a measure of light color)
- Thrips - wash with water well - scrub with makeup brush. Spray with Provanto (insecticide) Don't use on edibles.
- Spider mites - Wash with alcohol and water at ratio of 2/1 ratio. Really brush the mixture on the plant leaves. She did not say spray but I might try that. Spider mites don't fly so separate the plants first.
- Mealy bugs. Wash with direct alcohol. Takes 3 weeks or more of treatment - get it quarantined and keep it there! Keep spray8ing with Provanto.
- Aphids: Squash the aphids and wash the plant. Use brush and then spray with Provanto. Then prevent with Neem oil
- Fungus gnats: Keep the topsoil dry (they like wet soil) Pon is a non soil substitute. Gnats are in the soil. Repot is one option with non organic soil. Option is to spray the soil with hydrogen peroxide. "Mosquito bits" might work also *david had no luck with this.
Skills
- PVC
- cutting to length
- gluing
- Drilling or cutting plant holes
- Tapping for pipe fittings
- Lighting
- Pumping flow and pressure (calculations?)
Common Problems in Hydroponics
Generally this problem list includes:
- Leaking
- Lighting
- Water/Nutrients
- Fertilizer,
- pH,
- aeration
- Monitoring
- Not changing often enough
- Plant Medium
- Cleaning
- General plant monitoring (disease, growth, light, nutrients, cleaning, etc.
- Poor design for access and water and light
Here is a good article Links to an external site. on problems.
Random videos
This is no circulation - just head space