Hydroponics Apparatus
Design considerations
There are several design considerations to take into account:
- Space (maximize number of plants per volume unit)
- Parts (minimize number of parts)
- Energy (minimize energy consumption)
- Water (minimize water consumption)
- Nutrient requirements
- Yield (maximize yield and minimize time between harvests)
- Usability (simplify installation, use and maintenance)
- Risk mitigation (see corresponding chapter below)
There aren't always perfect solutions, but instead tread-offs between different design factors.
Use of space
Ideally, you want to grow as many plants as possible per unit of volume. Different systems, i.e. combinations of Hydroponics methods and System Designs, allows for different number of plants per cubic meter.
| Plants / m3 | Method | Design | Calculation (plants / m3) | Example product link | |
|---|---|---|---|---|---|
| 49.6 | NFT | Rack | n/V = 96/(1.3*0.85*1.75) = 96/1.934=49.6 | https://cityfarm.my/products/city-vertical-farm-xl-indoor-nft-system | |
| 104.8 | NFT | Tower | n/V = 80/(0.67*0.67*1.7) = 80/0.763 = 104.8 | https://www.alibaba.com/product-detail/Tower-Hydroponic-Grow-Systems-Complete-Vertical_1600065843280.html?spm=a2700.galleryofferlist.normal_offer.d_image.4a745dd9wib41C&s=p | |
| 214.3 | NFT | Rack | n/V = 108/(0.96*0.5*1.05) = 108/0.504=214 | https://www.alibaba.com/product-detail/Hydroponics-Nft-System-with-108-Holes_60827073175.html?spm=a2700.galleryofferlist.topad_classic.10.44e86ededHBbuX |
Parts
Ideally, you want to minimize the number of parts. Typically a hydroponic systems include the following parts:
NFT System
- Water reservoir
- Submersible electric pump
- Pipes (to fit net pots into)
- Net pots (to put substrate into)
- Substrate (to put seeds or seedlings into)
- Tubes (to connect pipes)
Kratky system
- Water reservoir
- Lid (with holes to fit net pots into)
- Net pots (to put substrate into)
- Substrate (to put seeds or seedlings into)
Energy
Ideally, you want to minimize the energy consumption required to run the system. However, trade-offs can be made to maximize yield; a system with a pump, grow lights, fans, etc. may produce more food of higher quality in less time than a passive (non-electric) hydroponic system.
Electronic components of a hydroponic system can include:
- Pump
- Grow lights
- Fans
- Automatic nutrient feeder
- Automatic harvesting function
- Sensors (for temperature, water pH, nutrient levels, etc.)
Water
Ideally, you want to minimize water consumption. Hydroponics is already an effective way to conserve water compared with growing plants in soil.
Be aware that grey water (water from doing dishes, taking showers, etc.) cannot be used in hydroponics. It can be harmful to eat plants from grey water, therefore only white water should be used for hydroponics (clean water free from soap, fat or oil from cooking, human skin particles, etc.) Grey water is only an option if you are growing is soil, but even then it has to be done the right way with regards to selection of soap, etc. Black water (containing human waste) should never be used.
Nutrient requirements
The "Nutrients solution" chapter on Wikipedia's Hydroponics page is extensive and will provide a good start for looking into nutrient requirements.
Managing nutrient concentrations and pH values within acceptable ranges is essential for successful hydroponic horticulture. Common tools used to manage hydroponic solutions include:
- Electrical conductivity meters, a tool which estimates nutrient ppm by measuring how well a solution transmits an electric current.
- pH meter, a tool that uses an electric current to determine the concentration of hydrogen ions in solution.
- Litmus paper, disposable pH indicator strips that determine hydrogen ion concentrations by color changing chemical reaction.
- Graduated cylinders or measuring spoons to measure out premixed, commercial hydroponic solutions.
Yield
Ideally, you want to maximize yield; the amount of food produced in a given time period. Yield can be maximized through the following factors:
- Growing method
- Light; grow lights with the optimal frequency and distance from plants
- Temperature; sensors for measuring temperature in water and air, heaters
- Nutrients; sensors measuring nutrient levels in water
- Humidity; humidifiers
- Air flow; fans
Grow tents can be used for to create a controlled mini-environment for plants, functioning as a mini greenhouse.
Usability
Installation The number of parts and their design is a factor.
Maintenance
Maintenance may include
- cleaning of pipes
- replacing parts
Use
Use may include
- refilling water reservoir
- putting seeds and seedlings into substrate
- managing nutrient levels
- harvesting
Ideally, the system shall be designed to be used with ease and good ergonomics.
Risks
| Risk | Mitigation | Comment | |
|---|---|---|---|
| Algae and microbe growth inside system |
|
Algae requires light to grow and can be combated by limiting the amount of light that reaches inside the system. | |
| Clogged pipes | Use pipes with a wide enough diameter to fit the plants' root systems | Small leafy greens such as lettuce, can grow easily with pipes as narrow as 6 cm in diameter, but tomatoes have larger root systems that require larger pipes. Grow tower designs that have been used for tomatoes often have a diameter of 30 cm or wider. | |
| Plastic contamination | If plastic is used in the hydroponic system, use food graded plastic | PVC is a common plastic used in hydroponics. If no plasticizers are added, it is known as uPVC or Rigid PVC (Food Safe PVC). uPVC or Rigid PVC does not contain any phthalates or BPA and is safe and stable. |
Design Rationale
The purpose of the Hydroponics Apparatus is to create structure that has a large amount of thermal mass, is sourced from local materials, and allows the root zone of all plants being cultivated to be exposed to the nutrients it needs to maximize growth, while minimizing risk factors posed by disease, pest infestation, and prolonged removal from the fluid interface. Additionally, it should be as handicap-accessible as possible.
Function
This greenhouse module will be tied in to the Spirulina/Crayfish/Aquaponics pools recursively; the waste cycles of the Spirulina/Crayfish/Aquaponics pools will not flow directly into the hydroponics apparatus, but the fertigation fluid in the hydroponics apparatus will flow into a biofilter assembly and then, via a 12 inch drop to reoxygenate the fluid, into the spirulina/crayfish and Trout/Perch. The vast majority of the hydroponics apparatus will be an "aquaduct" style floating raft system for cultivation of leafy vegetables, 3 compressed earth bricks wide, 2 deep approximately 32 inches above the floor. Another significant part of the aquaponics assembly will dutch bucket systems for cultivation of taller fruiting plants, such as tomatoes, peppers, and the like.
Inputs
LED lighting (Red and Blue spectrums) Compost Tea Fertigation mixture Seedlings Vermiculite Rockwool Diatomacious Earth Ladybugs Praying Mantis Bumblebees Cat (Rodent control) Vinegar Garlic
Outputs
Year-round vegetables, including Tomatoes, Kale, Celery, Swiss Chard, Lettuce, Peppers, Ashitaba, Spinach, Basil, etc.