Hydroponic Growing System
Hydroponics involves growing wants in nutrient water rather than soil. Although there are many benefits in growing plants in this manner, their are also some challenges that must be met.
Aeration
Oxygen in the water is one of the most important necessities in any hydroponic system. If you were water your house plant too much it would probably die. This is because your plant would develop root rot. That is the growth of Anaerobic bacteria or bacteria that grows in the absence of oxygen. If oxygen is present, these bacteria will not grow or die (meaning they are obligate anaerobes).
DWC solves this problem by using air pump and air stones to bubble air through the water. The bubbles increase the surface area in which the oxygen can dissolve into the water. Kratky's method takes a different approach to this problem. Because all the pumps and stones will get expensive for large systems, Kratky's method does not require pumps of any kind. Instead it has a much lower water level with the plants hanging above. This leaves the majority of the roots exposed to air.
For our system we have a slightly higher water levels that reduce the need to monitor the water level as well as increase the amount of nutrients the plants take up. By incorporating Kratky's methodology we have been able to greatly reduce the amount of air pumps needed with a conventional DWC system.
Hydroponics involves growing wants in nutrient water rather than soil. Although there are many benefits in growing plants in this manner, their are also some challenges that must be met.
Aeration
Oxygen in the water is one of the most important necessities in any hydroponic system. If you were water your house plant too much it would probably die. This is because your plant would develop root rot. That is the growth of Anaerobic bacteria or bacteria that grows in the absence of oxygen. If oxygen is present, these bacteria will not grow or die (meaning they are obligate anaerobes).
DWC solves this problem by using air pump and air stones to bubble air through the water. The bubbles increase the surface area in which the oxygen can dissolve into the water. Kratky's method takes a different approach to this problem. Because all the pumps and stones will get expensive for large systems, Kratky's method does not require pumps of any kind. Instead it has a much lower water level with the plants hanging above. This leaves the majority of the roots exposed to air.
For our system we have a slightly higher water levels that reduce the need to monitor the water level as well as increase the amount of nutrients the plants take up. By incorporating Kratky's methodology we have been able to greatly reduce the amount of air pumps needed with a conventional DWC system.
Lighting
The type of lighting is one of the most important factors that will affect the photosynthetic efficiency of our plants. As you can see in the graph to the right, only a certain portion of the visible light spectrum can be used to support photosynthesis.
Colour is often measured in Kelvin or K. Higher Kelvin lighting like 6000K produces more blue and purple light whereas 1500K lights produce more red light. Both produce photosynthetically active light but in our project we will be using 6000k lights as we are going purely for vegetative growth. The more red lights signal are similar to the type of sunlight you see around the end of the growing season. This tells the plants that winter will be coming soon and would make our lettuce bolt (start producing flowers and seeds) earlier.
The type of lighting is one of the most important factors that will affect the photosynthetic efficiency of our plants. As you can see in the graph to the right, only a certain portion of the visible light spectrum can be used to support photosynthesis.
Colour is often measured in Kelvin or K. Higher Kelvin lighting like 6000K produces more blue and purple light whereas 1500K lights produce more red light. Both produce photosynthetically active light but in our project we will be using 6000k lights as we are going purely for vegetative growth. The more red lights signal are similar to the type of sunlight you see around the end of the growing season. This tells the plants that winter will be coming soon and would make our lettuce bolt (start producing flowers and seeds) earlier.
Fertilizer concentration and pH
As our hydroponic system is a closed system, we minimize the loss of water and has made fertilizer run-off a thing of the past. We simply need to replace any water and nutrients the plants use as they grow.
To do so we measure the ppm (parts per million) of dissolved solutes and calculate precisely how much nutrients we need to add. By doing so we can keep the nutrient levels at optimal levels consistently (1250 ppm +/- 100).
pH is also very important as plants prefer slightly acidic water at a pH of 5.5 to 6.0. To determine exactly how much acid is needed in the water we tried to calculate it using the formula pH= -log[H+] but because of the presence of buffers we needed to perform an acid-base titration, graph our data and use the graph to extrapolate the acid requirements needed for a given pH.
As our hydroponic system is a closed system, we minimize the loss of water and has made fertilizer run-off a thing of the past. We simply need to replace any water and nutrients the plants use as they grow.
To do so we measure the ppm (parts per million) of dissolved solutes and calculate precisely how much nutrients we need to add. By doing so we can keep the nutrient levels at optimal levels consistently (1250 ppm +/- 100).
pH is also very important as plants prefer slightly acidic water at a pH of 5.5 to 6.0. To determine exactly how much acid is needed in the water we tried to calculate it using the formula pH= -log[H+] but because of the presence of buffers we needed to perform an acid-base titration, graph our data and use the graph to extrapolate the acid requirements needed for a given pH.
Temperature Control
High temperatures can drastically reduce the productivity and taste of most vegetation. This is because of the enzyme rubisco (or ribulose biphosphate carboxylase oxygenase). This enzyme that normally fixes carbon dioxide into glucose (sugar) but as temperatures rise above 25 degrees Celsius this enzyme does its job in reverse. This makes lettuce get bitter in the later months of summer.
Because our hydroponic system is indoors we will easily be able to grow the best tasting lettuce all year round. Keeping the water cool also increases the amount of oxygen that can dissolve into the water as the solubility of gases decreases as temperatures increase.
High temperatures can drastically reduce the productivity and taste of most vegetation. This is because of the enzyme rubisco (or ribulose biphosphate carboxylase oxygenase). This enzyme that normally fixes carbon dioxide into glucose (sugar) but as temperatures rise above 25 degrees Celsius this enzyme does its job in reverse. This makes lettuce get bitter in the later months of summer.
Because our hydroponic system is indoors we will easily be able to grow the best tasting lettuce all year round. Keeping the water cool also increases the amount of oxygen that can dissolve into the water as the solubility of gases decreases as temperatures increase.